Mercedes-Benz2004–2023 Critical issues documented

Mercedes-Benz A-Class W177: common faults & what to check

The W177 is the Mercedes-Benz A-Class built 2018 onward. It was sold here with the 1.3 turbo petrol and 2.0 turbo (A35). Of the 23 faults documented for the A-Class, 11 apply to this generation, each with its symptoms, what to inspect and a typical repair cost. Free, no account needed.

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Documented faults

Critical

Most serious

$500–$2,800

Typical repair

Systems covered

You're looking at the W177

2 engine variants are documented for this generation. Pick yours to narrow further, or keep reading for the generation as a whole.

Mercedes-Benz A-Class, W177 (2018–now) (KickTyres illustration)

2018–nowW177 Selected2018–nowW1771.3 turbo petrolPetrolDocumented issues7 knownSee faults & what to checkKickTyres illustration, not a photograph.

2018–nowW177 Selected2018–nowW1772.0 turbo (A35)Fuel not statedDocumented issues8 knownSee faults & what to checkKickTyres illustration, not a photograph.

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Now narrow it to the engine

A 1.8 and a 2.4 of the same car do not fail the same way, so the faults below narrow to the engine as well as the year. Free, no account needed.

Which engine is in it?

1.3 turbo petrol· 1.3 litre petrol, turbocharged 2.0 turbo (A35)· 2.0 litre, turbocharged

A 2020 Mercedes-Benz A-Class is the W177 generation (2018 to now).

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Mercedes-Benz A-Class W177Engine not picked yet

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Can't confirm for this car

Mercedes-Benz A-Class · 2020

Narrowed to the year. No engine is recorded for this vehicle. Pick an engine to see which faults apply.

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No engine is recorded for this vehicle.

matched on year only

What to look out for

The checks worth doing on a Mercedes-Benz A-Class before you hand over any money. Every documented fault is listed below, each with its own page.

Costly issue
Check for uneven tyre wear on the front axle (inner or outer edge wear).
See why
Front Subframe and Lower Control Arm Bushing Premature Wear
The W177 A-Class uses an aluminium front subframe with rubber-bonded control arm bushings that are documented to wear prematurely, particularly on vehicles used in urban environments with frequent low-speed impacts (speed bumps, potholes). Worn bushings cause steering vagueness, clunking on bump inputs, and tracking instability. This is exacerbated on vehicles fitted with the optional AMG Line lowered suspension. The bushings are not individually serviceable from many aftermarket suppliers, requiring control arm assembly replacement in some cases. European owner communities and independent workshop forums document this as a recurring fault from around 50,000 km.
What you would notice
- Clunking or knocking from front suspension over speed bumps or rough roads
- Steering wheel wander or vagueness at motorway speeds
- Uneven tyre wear on front axle, particularly inner edge
- Vehicle pulling to one side under braking
- Front-end vibration felt through steering wheel at low speeds on rough surfaces
Typically $500–$2,200 to put right.
Common issue
Spend 10 minutes working the system hard on the test drive: pair a phone, run navigation, switch between menus, use 'Hey Mercedes'.
See why
MBUX infotainment freezes, black screens and phantom faults
Early W177s pioneered the MBUX twin-screen system and it shipped buggy: frozen or black screens, reboots while driving, lost Bluetooth/CarPlay, and spurious warning messages. Most issues are fixed by dealer software updates, but a car that has never been updated will still misbehave, and a genuinely faulty head unit or screen is expensive outside warranty.
What you would notice
- Screens freeze or go black mid-drive
- System reboots itself
- CarPlay/Android Auto drops out
- Random warning chimes or messages
Typically $200–$3,500 to put right.
Common issue
During test drive, verify the MBUX screen responds without lag or freezing across multiple menu inputs.
See why
MBUX Infotainment Head Unit Freezing and Black Screen
Early W177 builds (2018-2021) with the first-generation MBUX infotainment system experienced freeze and black screen events due to insufficient RAM management and software memory leaks in the head unit. The screen would go blank or lock up requiring a hard reset (holding the volume knob). Mercedes-Benz issued multiple OTA and dealer software updates to address the issue, but some units required head unit replacement when flash updates failed to resolve repeated lockups. This fault affects the safety-relevant reversing camera display and parking sensor readout.
What you would notice
- Infotainment screen going blank/black while driving without recovering
- Touch screen becoming unresponsive requiring manual hard reset
- Reversing camera failing to display image when reverse gear is selected
- Navigation or audio app crashing and restarting mid-journey
- MBUX system boot taking over 60 seconds after cold start
Typically $0–$2,500 to put right.
Worth checking
Cold-start the engine and listen for rattling from the front of the engine (serpentine belt / BSG area) for the first 10-30 seconds.
See why
48V Belt-Starter-Generator (BSG) Rattle and Failure on EQ Boost Variants
A-Class A 250 e and certain A 200 / A 220 EQ Boost variants with the 48V mild hybrid system use a belt-driven starter-generator (BSG) on the front accessory drive. The BSG tensioner and belt are known to produce a rattling or scraping noise on cold starts as the belt stretch exceeds tensioner travel. In more advanced cases the BSG itself develops bearing noise or fails electrically, causing loss of the mild hybrid boost function and triggering a 48V system fault. Replacing the belt and tensioner is the initial remedy; BSG replacement is required for electrical failure.
What you would notice
- Rattling or slapping noise from front of engine on cold start, disappearing after warm-up
- Yellow 48V system warning in instrument cluster
- Loss of EQ Boost mild hybrid assist (noticeable as reduced low-speed pull)
- Increased fuel consumption without other explanation
- Belt tensioner squealing under engine load
Typically $350–$3,500 to put right.
Worth checking
Check that the TPMS warning light on the dashboard extinguishes after driving 5+ minutes at over 40 km/h with correct tyre pressures.
See why
TPMS Sensor Failure and False Tyre Pressure Warnings
The W177 A-Class uses battery-powered direct TPMS sensors in each wheel. Sensor battery life is typically 5-7 years, and first-generation W177 vehicles (2018-2019) are now entering the window where sensors fail and cause persistent low-pressure warnings that cannot be cleared. Sensors also fail after tyre replacements if the sensor housing is damaged. Mercedes-Benz has no recall but the fault is widely reported and requires individual sensor replacement at typically $120-180 NZD per corner plus programming with STAR Diagnosis.
What you would notice
- Persistent low tyre pressure warning even after inflating all tyres to correct pressure
- TPMS warning light that cannot be reset via the instrument cluster menu
- One wheel position showing no pressure reading in the TPMS display
- Intermittent pressure readings that jump between correct and zero
- Warning appearing after a tyre rotation or replacement
Typically $150–$700 to put right.

See all 11 issues for this oneDocumented for the exact year and engine you picked.

Electrical4

0148V Belt-Starter-Generator (BSG) Rattle and Failure on EQ Boost Variants

Cold-start the engine and listen for rattling from the front of the engine (serpentine belt / BSG area) for the first 10-30 seconds.petrol2019–2023Electrical$350–$3,500

OccasionalElectrical $350–$3,500 to fix

A-Class A 250 e and certain A 200 / A 220 EQ Boost variants with the 48V mild hybrid system use a belt-driven starter-generator (BSG) on the front accessory drive. The BSG tensioner and belt are known to produce a rattling or scraping noise on cold starts as the belt stretch exceeds tensioner travel. In more advanced cases the BSG itself develops bearing noise or fails electrically, causing loss of the mild hybrid boost function and triggering a 48V system fault. Replacing the belt and tensioner is the initial remedy; BSG replacement is required for electrical failure.

Symptoms to notice

Rattling or slapping noise from front of engine on cold start, disappearing after warm-up
Yellow 48V system warning in instrument cluster
Loss of EQ Boost mild hybrid assist (noticeable as reduced low-speed pull)
Increased fuel consumption without other explanation
Belt tensioner squealing under engine load

What to check

Cold-start the engine and listen for rattling from the front of the engine (serpentine belt / BSG area) for the first 10-30 seconds. Check the instrument cluster for any 48V or EQ Boost warning icons. With STAR Diagnosis, read 48V system voltage and BSG current output values.

Where to look: Front of engine, serpentine/accessory belt drive area; 48V battery in boot/under rear seat

Parts involved: Starter motor.

Ask the seller

“Does the car make a rattling noise from the engine bay on a cold start?”
“Has a 48V system or EQ Boost warning ever appeared on the dashboard?”
“Has the BSG belt or tensioner ever been replaced?”

02MBUX infotainment freezes, black screens and phantom faults

Spend 10 minutes working the system hard on the test drive: pair a phone, run navigation, switch between menus, use 'Hey Mercedes'.2018 onwardElectrical$200–$3,500

CommonElectrical $200–$3,500 to fix

Early W177s pioneered the MBUX twin-screen system and it shipped buggy: frozen or black screens, reboots while driving, lost Bluetooth/CarPlay, and spurious warning messages. Most issues are fixed by dealer software updates, but a car that has never been updated will still misbehave, and a genuinely faulty head unit or screen is expensive outside warranty.

Symptoms to notice

Screens freeze or go black mid-drive
System reboots itself
CarPlay/Android Auto drops out
Random warning chimes or messages

What to check

Spend 10 minutes working the system hard on the test drive: pair a phone, run navigation, switch between menus, use 'Hey Mercedes'.
Ask the dealer/seller when the last MBUX software update was performed.
Check every screen pixel-perfect at different brightness levels.

Where to look: Dashboard twin displays and head unit behind them

Ask the seller

“Has the MBUX software been updated at a dealer?”
“Any history of screen replacement or freezes?”

03MBUX Infotainment Head Unit Freezing and Black Screen

During test drive, verify the MBUX screen responds without lag or freezing across multiple menu inputs.2018–2021Electrical$0–$2,500

CommonElectrical $0–$2,500 to fix

Early W177 builds (2018-2021) with the first-generation MBUX infotainment system experienced freeze and black screen events due to insufficient RAM management and software memory leaks in the head unit. The screen would go blank or lock up requiring a hard reset (holding the volume knob). Mercedes-Benz issued multiple OTA and dealer software updates to address the issue, but some units required head unit replacement when flash updates failed to resolve repeated lockups. This fault affects the safety-relevant reversing camera display and parking sensor readout.

Symptoms to notice

Infotainment screen going blank/black while driving without recovering
Touch screen becoming unresponsive requiring manual hard reset
Reversing camera failing to display image when reverse gear is selected
Navigation or audio app crashing and restarting mid-journey
MBUX system boot taking over 60 seconds after cold start

What to check

During test drive, verify the MBUX screen responds without lag or freezing across multiple menu inputs.
Check the software version in Settings > About.
Confirm reversing camera activates immediately when reverse is selected (delays or black camera screen are a symptom).
Ask owner about any head unit replacements under warranty.

Where to look: Central dashboard MBUX head unit and associated computing module behind dashboard

Ask the seller

“Has the MBUX screen ever frozen or gone black while driving?”
“Has the head unit software been updated at a dealership?”
“Does the reversing camera always display immediately when you select reverse?”

04TPMS Sensor Failure and False Tyre Pressure Warnings

Check that the TPMS warning light on the dashboard extinguishes after driving 5+ minutes at over 40 km/h with correct tyre pressures.2018–2023Electrical$150–$700

OccasionalElectrical $150–$700 to fix

The W177 A-Class uses battery-powered direct TPMS sensors in each wheel. Sensor battery life is typically 5-7 years, and first-generation W177 vehicles (2018-2019) are now entering the window where sensors fail and cause persistent low-pressure warnings that cannot be cleared. Sensors also fail after tyre replacements if the sensor housing is damaged. Mercedes-Benz has no recall but the fault is widely reported and requires individual sensor replacement at typically $120-180 NZD per corner plus programming with STAR Diagnosis.

Symptoms to notice

Persistent low tyre pressure warning even after inflating all tyres to correct pressure
TPMS warning light that cannot be reset via the instrument cluster menu
One wheel position showing no pressure reading in the TPMS display
Intermittent pressure readings that jump between correct and zero
Warning appearing after a tyre rotation or replacement

What to check

Check that the TPMS warning light on the dashboard extinguishes after driving 5+ minutes at over 40 km/h with correct tyre pressures. If the light remains on with correct pressures, a sensor fault is likely. Ask if any sensors have been replaced. Early 2018-2019 builds are highest risk.

Where to look: Inside each wheel rim, valve-stem mounted sensor unit

Ask the seller

“Has a tyre pressure warning light appeared with correctly inflated tyres?”
“Have any TPMS sensors been replaced since new?”
“Have any tyres been replaced and was TPMS re-programmed afterwards?”

Body, brakes, suspension & interior1

05Front Subframe and Lower Control Arm Bushing Premature Wear

Check for uneven tyre wear on the front axle (inner or outer edge wear).2018–2023Suspension$500–$2,200

OccasionalSuspension $500–$2,200 to fix

The W177 A-Class uses an aluminium front subframe with rubber-bonded control arm bushings that are documented to wear prematurely, particularly on vehicles used in urban environments with frequent low-speed impacts (speed bumps, potholes). Worn bushings cause steering vagueness, clunking on bump inputs, and tracking instability. This is exacerbated on vehicles fitted with the optional AMG Line lowered suspension. The bushings are not individually serviceable from many aftermarket suppliers, requiring control arm assembly replacement in some cases. European owner communities and independent workshop forums document this as a recurring fault from around 50,000 km.

Symptoms to notice

Clunking or knocking from front suspension over speed bumps or rough roads
Steering wheel wander or vagueness at motorway speeds
Uneven tyre wear on front axle, particularly inner edge
Vehicle pulling to one side under braking
Front-end vibration felt through steering wheel at low speeds on rough surfaces

What to check

Check for uneven tyre wear on the front axle (inner or outer edge wear). On the test drive, note any steering vagueness or knocking over speed bumps from the front of the car. If a workshop inspection is possible: With the car on a hoist, grab each front wheel at 9 and 3 o'clock and apply lateral force — any clunk or movement indicates worn control arm bushings.

Where to look: Front axle subframe, lower control arm inner pivot bushings both sides

Ask the seller

“Has the car ever had front suspension bushings or control arms replaced?”
“Does the car make any knocking sounds from the front over speed bumps?”
“When were the front tyres last aligned, and were any wear issues noted?”

Depends on the exact engine — 6 moreDocumented for a specific engine we could not confirm from what you picked. Check the engine code on the car.

Engine, transmission & cooling6

01M282 1.3T Timing Chain Wear (Renault-Sourced Engine)

Cold-start and listen for chain rattle from the engine cover area in the first 5 seconds.petrol2018 onwardEngineCan't confirm for this car$1,800–$4,000

OccasionalEngine $1,800–$4,000 to fix

Can't confirm for this car

The M282 1.3-litre turbocharged petrol engine co-developed with Renault, fitted to W177 A180 and A200, carries over the hydraulic tensioner timing chain architecture of earlier Mercedes four-cylinders. Early production engines have documented cold-start timing chain rattle and tensioner wear. The engine is shared with Renault Megane and has consistent reports across both marques for chain stretch from 60,000 km on neglected oil service schedules.

Symptoms to notice

Cold-start chain rattle lasting more than 1–2 seconds
Cam/crank correlation fault codes on OBD scan
Rough idle on cold start that clears as engine warms
Increased oil consumption in higher-mileage examples

What to check

Cold-start and listen for chain rattle from the engine cover area in the first 5 seconds. Review oil service intervals — this engine is sensitive to extended intervals or incorrect oil viscosity. Cross-reference with Renault Megane 1.3 TCe reports for the same engine fault patterns. If a workshop inspection is possible: Pull OBD fault codes for P0016/P0017.

Where to look: Top front of engine, timing chain cover behind plastic engine cover

Parts involved: Timing chain.

Ask the seller

“Has the timing chain or tensioner been inspected or replaced?”
“What oil intervals have been used and which specification?”
“Has a cold-start rattle ever been noticed?”

02OM608 1.5D DPF Blockage in Short-Trip / Urban Use

Ask owner about typical journey length.diesel2018–2023EngineCan't confirm for this car$300–$3,800Read the full fault: symptoms, where to look, what to ask the seller

038G-DCT Dual Clutch Transmission Shudder and Judder

Test drive at slow crawling speeds (5-20 km/h) in traffic; feel and listen for vibration or shudder through drivetrain.petrol2018–2023TransmissionCan't confirm for this car$400–$2,800Read the full fault: symptoms, where to look, what to ask the seller

04OM654 / OM608 EGR Valve Sticking and Carbon Build-up

Scan for EGR-related fault codes (P0401, P0402, P040D range) with STAR Diagnosis.diesel2018–2023EngineCan't confirm for this car$400–$2,500

OccasionalEngine $400–$2,500 to fix

Can't confirm for this car

Both diesel variants (OM608 1.5D and OM654 2.0D) use exhaust gas recirculation (EGR) systems that are prone to carbon build-up causing the EGR valve to stick open or closed. A stuck-open EGR causes rough idle, increased smoke, and loss of power. A stuck-closed EGR causes NOx-related faults and potential emission test failure. The OM654 in particular shows documented EGR cooler coolant leaks in addition to valve sticking, a pattern shared with the same engine in C-Class and E-Class applications. Mercedes-Benz has issued EGR cleaning and replacement procedures.

Symptoms to notice

Rough idle or hunting idle when engine is at operating temperature
Black smoke from exhaust under light throttle at idle
Engine warning light with EGR flow or position fault codes
Coolant loss without visible external leak (OM654 EGR cooler breach)
Increased fuel consumption and reduced throttle response

What to check

Scan for EGR-related fault codes (P0401, P0402, P040D range) with STAR Diagnosis.
Check for rough idle or smoke at idle when engine is warm.
Inspect coolant level for unexplained loss (OM654 EGR cooler leak).
Check for black carbon deposits around the EGR valve housing and inlet manifold.

Where to look: EGR valve and cooler on side of engine block, inlet manifold area

Parts involved: EGR valve.

Ask the seller

“Has an engine warning light related to the EGR or emissions ever appeared?”
“Has the car ever required an EGR valve clean or replacement?”
“Has coolant needed topping up between services?”

05M260 / M264 Electric Water Pump Bearing and Impeller Failure

Check coolant level and condition (milky or low coolant is a red flag).petrol2018–2022CoolingCan't confirm for this car$600–$2,200Read the full fault: symptoms, where to look, what to ask the seller

06M282 1.33 turbo — coolant leaks from thermostat/water pump housing area

petrol2018 onwardCoolingCan't confirm for this car$600–$1,800

OccasionalCooling $600–$1,800 to fix

Can't confirm for this car

The Renault-Mercedes co-developed 1.33-litre M282 in A180/A200 models has a documented pattern of coolant loss from the plastic thermostat housing and water pump area, plus occasional low-coolant warnings from small system leaks. Caught early it is a modest repair; ignored, overheating an alloy small-capacity turbo engine causes head gasket or engine damage.

An annotated photograph of an automotive engine thermostat identifying the wax capsule and both disc valves. — A double-valve engine thermostat, labelled: the wax capsule is what sticks.
Dougsim · CC BY-SA 3.0 · Wikimedia Commons

Symptoms to notice

Low coolant warning
Sweet smell after parking
Dried pink/white coolant residue on the engine front
Coolant level dropping between checks

What to check

With the engine cold, check the coolant expansion tank is at the correct level and look for crusty residue around the thermostat housing at the front of the engine and below it on the subframe. After the test drive, sniff for a sweet coolant smell in the engine bay.

Where to look: Front/side of engine — thermostat and water pump housings; expansion tank on the right

Parts involved: Water pump, Thermostat, Turbocharger.

Ask the seller

“Has it ever needed coolant topped up between services?”
“Any cooling system parts replaced?”

Other Mercedes-Benz A-Class engines and years12 documented issues that do not apply to the one you picked.

Engine, transmission & cooling7

01Turbo failure from contaminated oil feed line (A 45 AMG 2.0 M133 turbo, W176)

Perform a cold start and observe the exhaust for blue smoke.petrol2013–2015EngineDoes not apply$3,500–$9,000

OccasionalEngine $3,500–$9,000 to fix

Does not apply

On the W176 A 45 AMG with the 2.0 M133 turbo petrol, the strainer in the turbocharger oil feed line could become contaminated, starving the turbo bearings of oil and wearing them out early. Mercedes ran service campaign 2014120001 on early M133 cars (the CLA 45 and GLA 45 are documented, and an Australian specialist source lists the A 45): dealers measured turbo shaft play and replaced the turbo and oil feed lines when it was over 0.08 mm, which about a quarter of cars needed. Ask a Mercedes dealer whether the campaign was completed on the VIN, and treat smoke or a siren-like whistle under boost as a worn turbo.

Symptoms to notice

Blue or grey smoke from exhaust particularly on cold start or under boost
Turbo whine, whistle, or surge sound under hard acceleration
Increased oil consumption between service intervals
Loss of boost pressure or noticeably reduced power output
Oil leaking from turbocharger centre section seals

What to check

Perform a cold start and observe the exhaust for blue smoke. Accelerate firmly through the rev range and check for unusual turbo whistle or boost surge. Review oil change history for correct specification and intervals under 7,500km. Ask about any history of turbo-related fault codes. If a workshop inspection is possible: Remove the intercooler inlet hose and inspect for oil film indicating turbo seal failure. A borescope inspection of the turbo oil feed line is advisable on high-mileage examples.

Where to look: Turbocharger unit and oil feed line running from cylinder head to turbocharger

Parts involved: Turbocharger.

Ask the seller

“Has the turbocharger ever been replaced or inspected for wear?”
“What is the oil change interval and specification used throughout?”
“Is there any history of blue smoke from the exhaust or elevated oil consumption?”
“Has the turbo oil feed line been replaced or cleaned as a preventive measure?”

02Autotronic CVT (722.8) failure — shudder, limp mode, total loss of drive

Test drive from cold: pull away gently and then briskly, feeling for shudder or slipping.2005–2012TransmissionDoes not apply$3,500–$7,000Read the full fault: symptoms, where to look, what to ask the seller

03OM640 Timing Chain Guide Cracking and Debris Contamination

Drain and inspect oil for plastic debris or metallic swarf.diesel2004–2012EngineDoes not apply$2,200–$5,000

OccasionalEngine $2,200–$5,000 to fix

Does not apply

The OM640 2.0D diesel in the W169 A180 CDI and A200 CDI suffers from timing chain guide cracking, releasing plastic fragments into the oil circuit. Unlike petrol variants the noise signature can be masked by normal diesel clatter. Debris blocking oil galleries can cause bearing damage beyond the chain itself.

Symptoms to notice

Intermittent rattle on start-up, easily confused with normal diesel noise
Increased oil consumption
Oil pressure warning light
Camshaft position sensor fault codes

What to check

Drain and inspect oil for plastic debris or metallic swarf.
Cold-start the engine and listen carefully for chain rattle above the normal diesel clatter rhythm.
Check service history for oil change intervals — beyond 15,000 km intervals dramatically increase guide degradation.
Run fault code scan for cam/crank correlation errors.

Where to look: Front of engine block, timing chain cover, driver's side

Parts involved: Timing chain.

Ask the seller

“When was the last oil change and what interval was used?”
“Has any chain or guide work been done?”
“Has the car ever shown any rattle or oil warning?”

04M266 Timing Chain Stretch and Guide Failure

Start cold and listen for chain rattle from the top of the engine for the first 20–30 seconds.petrol2004–2012EngineDoes not apply$2,000–$4,500

CommonEngine $2,000–$4,500 to fix

Does not apply

The M266 2.0T engine fitted to W169 A-Class and W245 B-Class is prone to timing chain stretch and plastic chain guide cracking, especially when oil changes are neglected. The chain can skip teeth or snap, causing catastrophic valve-to-piston contact. Onset typically occurs from 80,000–130,000 km.

Symptoms to notice

Rattling or chattering noise on cold start from timing cover area
Check engine light with camshaft/crankshaft correlation codes (P0016, P0017)
Rough idle that worsens over time
Engine stall in severe cases

What to check

Start cold and listen for chain rattle from the top of the engine for the first 20–30 seconds.
Pull oil service records — intervals over 12,000 km sharply increase risk.
Request oil analysis or inspect for metallic debris in oil.
Check for stored fault codes related to cam/crank correlation.

Where to look: Front of engine, timing chain cover behind the auxiliary belt

Parts involved: Timing chain.

Ask the seller

“Has the timing chain or tensioner ever been replaced?”
“Can you show me the full oil service history?”
“Has the car ever shown a rattle on cold start?”

05M270 1.6/2.0 turbo timing chain guide wear, cold rattle (W176)

Start the engine cold and listen for rattling from the front-left of the engine bay before oil pressure builds.petrol2012–2018EngineDoes not apply$1,800–$3,800Read the full fault: symptoms, where to look, what to ask the seller

06OM640 diesel timing chain stretch and injector seal leaks

Cold-start the car yourself (feel the bonnet — it should be stone cold) and listen for a rattle in the first few seconds.diesel2005–2012EngineDoes not apply$1,800–$4,000

OccasionalEngine $1,800–$4,000 to fix

Does not apply

The OM640 CDI diesels in the W169 stretch their timing chains at higher mileage, giving a diesel rattle on cold start that worsens over time; left alone the chain can jump and wreck the engine. The same engines also suffer leaking copper injector seals ('black death' in mild form), leaving hard carbon deposits around the injectors and a diesel smell in the cabin. Both are well documented on Mercedes owner forums for this engine family.

Symptoms to notice

Metallic rattle for a few seconds on cold start
Diesel/exhaust smell from under the bonnet
Black tar-like crust around injectors
Chuffing noise at idle

What to check

Cold-start the car yourself (feel the bonnet — it should be stone cold) and listen for a rattle in the first few seconds. Remove the engine cover if the seller allows and look for black, baked-on deposits around the injector bases. Sniff for exhaust smell at idle with the bonnet open.

Where to look: Front of engine (timing chain) and top of engine under the plastic cover (injectors)

Parts involved: Fuel injector, Timing chain.

Ask the seller

“Has the timing chain ever been replaced?”
“Have any injector seals been done?”
“What oil grade and change interval has it had?”

07OM651 Diesel Particulate Filter Blockage (Short-Trip Driving)

Ask the owner how the car is used — predominantly urban/short-trip driving in Auckland, Wellington or Australian cities is a red flag.diesel2012–2018EngineDoes not apply$700–$2,800

CommonEngine $700–$2,800 to fix

Does not apply

The OM651 2.1D diesel in the W176 A200 CDI and A220 CDI requires extended highway runs to complete active DPF regeneration cycles. Urban or short-trip use in NZ/AU prevents regeneration completion, causing progressive DPF blockage. A blocked DPF forces limp-home mode and eventual DPF replacement if not addressed with a forced regen cycle by a dealer.

Symptoms to notice

DPF warning light on dashboard
Reduction in engine power (limp mode)
Increased fuel consumption as regen attempts fail
White or grey smoke from exhaust during attempted regeneration

What to check

Ask the owner how the car is used — predominantly urban/short-trip driving in Auckland, Wellington or Australian cities is a red flag. Inspect for oil level rise (failed regeneration dumps fuel into oil). A forced regen may resolve a partial blockage but a fully blocked or cracked DPF requires replacement. If a workshop inspection is possible: Check for active DPF warning or history of DPF codes via OBD scan.

Where to look: Exhaust system, downstream of turbo, underneath the car

Parts involved: Diesel particulate filter.

Ask the seller

“Has the DPF warning light ever come on?”
“Is the car primarily used for short city trips?”
“Has the car ever had a forced DPF regeneration performed?”

Electrical3

01Steering column grounding recall, driver airbag can deploy without a crash (W176 A-Class, built before September 2017)

Ask for Mercedes paperwork showing campaign RC2437 was done, or have a Mercedes dealer check the VIN for open recalls.2012–2017ElectricalDoes not apply$0–$400

RareElectrical $0–$400 to fix

Does not apply

Every W176 A-Class built before September 2017 (all engines) was recalled in Australia because the steering column module is not grounded well enough, and with a faulty switch the driver airbag can go off without a crash (PRA 2018/16572, Mercedes campaign RC2437/A). The dealer adds a ground connection free of charge. A car that missed it shows no warning, so check the VIN.

Symptoms to notice

Usually none before the airbag fires
Airbag or SRS warning light on
Steering wheel switches or horn working intermittently

What to check

Ask for Mercedes paperwork showing campaign RC2437 was done, or have a Mercedes dealer check the VIN for open recalls.
Check the SRS warning light comes on at start up and goes out, and that the horn and steering wheel buttons all work.
If a workshop inspection is possible: have the dealer confirm the steering column ground connection is fitted and read the airbag fault memory.

Where to look: Steering column module behind the steering wheel

Ask the seller

“Has Mercedes recall RC2437 for the steering column been done?”
“Has the airbag warning light ever come on?”

02Electric power steering (EPS) column/motor failure

The W169 uses an electric power steering column, and the motor/torque sensor unit fails with age.2005–2012ElectricalDoes not apply$1,200–$3,000

CommonElectrical $1,200–$3,000 to fix

Does not apply

The W169 uses an electric power steering column, and the motor/torque sensor unit fails with age. Assistance cuts out intermittently or permanently, throwing a red steering warning and making the wheel very heavy — alarming mid-corner. Mercedes' fix is a complete steering column, which is expensive; some NZ auto-electrical specialists can repair the unit for less.

Symptoms to notice

Red steering-wheel warning light
Steering suddenly heavy, especially at parking speeds
Assistance comes and goes intermittently
Clicking or whirring from the column

What to check

With the engine running, turn the wheel lock to lock at a standstill — it should feel uniformly light with no dead spots, groans or momentary heaviness. Cycle the ignition a few times and check no steering warning appears. Scan for stored EPS fault codes if possible.

Where to look: Steering column behind the dashboard (electric motor on the column itself)

Parts involved: Steering rack.

Ask the seller

“Has the steering column or EPS motor ever been replaced?”
“Has a steering warning light ever appeared, even briefly?”

03A-Class starting current limiter overheating fire recall PRA 2017/16367 (W176 A-Class sold February 2015 to January 2017)

Ask the seller whether the starting current limiter (starter fuse) recall was done and ask for the Mercedes dealer record.2015–2017ElectricalDoes not apply$0–$400

OccasionalElectrical $0–$400 to fix

Does not apply

On W176 A-Class models (all engines) sold in Australia from 31 January 2015 to 31 January 2017, the starting current limiter can overheat if the starter is cranked again and again while the engine or gearbox is jammed. In Australia this was recalled in October 2017 (PRA 2017/16367, listed for the W176 A-Class range by sale date) because nearby parts can catch fire; Japan recalled the A 180, A 250 and A 45 for the same defect (Gai-2539), and the sister CLA was recalled in the USA (NHTSA 17V-114). The fix is an extra fuse in the starter feed, fitted free by a Mercedes dealer. Recalled cars are listed by VIN, so ask a Mercedes dealer to check this one.

Symptoms to notice

Usually no warning before the fault
Burning or melted plastic smell after repeated cranking
Starter cranks or clicks but the engine will not turn

What to check

Ask the seller whether the starting current limiter (starter fuse) recall was done and ask for the Mercedes dealer record. Ring a Mercedes dealer with the VIN to confirm recall status. At the viewing, sniff the engine bay for burnt plastic and check the car starts first time. If a workshop inspection is possible: have a Mercedes dealer confirm the extra fuse is fitted.

Where to look: Engine bay, starter motor power feed

Parts involved: Starter motor.

Ask the seller

“Has the starter current limiter recall been completed?”
“Has the car ever struggled to start?”
“Is there a Mercedes dealer recall record?”

Body, brakes, suspension & interior2

01Front Lower Control Arm Ball Joint Wear

With wheels straight, grab each front tyre at 9 and 3 o'clock and attempt to rock — lateral play indicates outer tie rod or ball joint.2004–2012SuspensionDoes not apply$500–$1,100

CommonSuspension $500–$1,100 to fix

Does not apply

W169 A-Class lower control arm ball joints wear prematurely, particularly on the New Zealand and Australian road network. The ball joint is integral to the arm, requiring full arm replacement rather than a separate joint. Worn joints cause vague steering, pulling, and rapid tyre wear on the inner edge.

Symptoms to notice

Clunking from front suspension over bumps or during braking
Vague or wandering steering feel
Inner edge tyre wear more rapid than outer
Pulling to one side under braking

What to check

With wheels straight, grab each front tyre at 9 and 3 o'clock and attempt to rock — lateral play indicates outer tie rod or ball joint. Then grasp at 6 and 12 and rock — vertical play points to the lower ball joint. Inspect rubber boot on each ball joint for cracking or grease loss. Check both sides as wear is often bilateral.

Where to look: Front axle, lower control arm, one each side

Parts involved: Ball joint.

Ask the seller

“Has the front suspension been inspected or serviced recently?”
“Does the car pull to one side or feel vague at motorway speed?”
“When were the tyres last rotated — any unusual wear pattern?”

02Takata airbag recall and interior rattles (panoramic roof, dash)

Run the VIN through the (NZ) or Mercedes-Benz recall lookup before purchase and confirm the Takata replacement shows as completed.2013–2018InteriorDoes not apply$0–$500Read the full fault: symptoms, where to look, what to ask the seller

Mercedes-Benz A-Class faults in detail

Narrowed to the Mercedes-Benz A-Class · 2020. Each of these has its own page: the symptoms, where to look, what to ask the seller and what the repair costs. Free, no account needed.

8G-DCT Dual Clutch Transmission Shudder and JudderMajor · Transmission M260 / M264 Electric Water Pump Bearing and Impeller FailureMajor · Cooling OM608 1.5D DPF Blockage in Short-Trip / Urban UseMajor · Engine

What these repairs cost on other cars

Some of the Mercedes-Benz A-Class’s documented faults are repairs other models share. Each page lists the documented NZ cost for every model it affects.

Other Mercedes-Benz models

Mercedes-Benz C-Class41 documented faults Mercedes-Benz E-Class23 documented faults Mercedes-Benz GLA21 documented faults Mercedes-Benz S-Class20 documented faults Mercedes-Benz GLC17 documented faults Mercedes-Benz Vito16 documented faults

Mercedes-Benz A-Class buyer questions

Is the Mercedes-Benz A-Class reliable?

Like any used car, it depends on the specific example and its service history. Across the 23 documented faults for the Mercedes-Benz A-Class, the recurring problem areas are engine, transmission, and electrical. A Mercedes-Benz A-Class with a full service history and no signs of the issues listed on this page can be a sound buy but each one needs to be checked individually before you commit.

What are the most common problems with a used Mercedes-Benz A-Class?

We've catalogued 23 known faults for the Mercedes-Benz A-Class, covering engine, transmission, and electrical. All 23 are written out in full on this page, with the symptoms to notice, what to inspect, and typical repair costs for each. Free to read, no account needed.

How much do repairs cost on a Mercedes-Benz A-Class?

Most single repairs on the Mercedes-Benz A-Class fall between $500–$2,800 at NZ independent-workshop rates. Some of the 23 documented faults cost less and a few cost considerably more, and no one car needs them all. Knowing which ones to look for before you view is what lets you negotiate the price down or walk away.

Should I get a pre-purchase inspection on a Mercedes-Benz A-Class?

Yes. A Mercedes-Benz A-Class inspection focused on its known weak points is the single best way to avoid an expensive mistake. KickTyres gives you a guided, model-specific inspection plus a market valuation and negotiation figure for $24.90 far less than the cost of missing one of the faults on this page.