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Mercedes-Benz2005–2019 Critical issues documented

Mercedes-Benz B-Class: common faults & what to check

Thinking about buying a used Mercedes-Benz B-Class (2005–2019) in New Zealand? We've documented 8 known faults for this model spanning transmission, engine, suspension, and cooling. Each researched and verified before it's published. The most serious issues here are rated critical. Every one is listed below with its symptoms and repair cost, and each has its own page with where to look and what to ask the seller. Free, no account needed.

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  • Money owing
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  • Ownership history
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  • NZ owned and operated

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8

Documented faults

Critical

Most serious

$1,500–$3,500

Typical repair

4

Systems covered

Which Mercedes-Benz B-Class are you looking at?

4 generation variants documented. Pick the shape you recognise: the faults, the servicing and the timeline below all narrow to it. Free, no account needed.

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? These cover every year of this model.

1.6 turbo petrol· 1.6 litre petrol, turbocharged2.0 petrol· 2.0 litre petrol

Start your free check on this Mercedes-Benz B-Class

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Mercedes-Benz B-ClassEngine not picked yet

Pick the engine above first: the B-Class came with 2, and without it the report has to show all of their faults. Pick the engine

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Can't confirm for this car

Mercedes-Benz B-Class

Nothing has been narrowed yet, so nothing below is a claim about a particular car. Pick a year and an engine to see which faults apply.

Tell us the engine, or check the engine code on the car, before relying on this.

matched on no vehicle context

What to look out for

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

  • Serious issue

    Test drive from cold and again after 15-20 minutes.

    See why

    Autotronic CVT (722.8) shudder, jerking and failure (W245)

    The first-generation B-Class shares the A-Class's Autotronic continuously variable transmission, and it is the generation's most expensive weak point. The belt/pulley pack and its electrohydraulic control unit wear out, causing shudder pulling away, hesitation, flaring revs and eventually limp mode or no drive. Mercedes treated the fluid as 'sealed for life', which accelerated wear, so a car with no CVT fluid history is higher risk. A rebuild or replacement usually costs more than a tidy W245 is worth.

    What you would notice

    • Shudder or juddering when pulling away
    • Revs rise but speed does not follow
    • Hesitation or jerk when accelerating from a stop
    • Transmission warning symbol on the dash
    • Slips into limp mode on a longer test drive

    Typically $4,000–$8,000 to put right.

  • Costly issue

    Perform a cold-start test — listen for chain rattle in the first 5 seconds.

    See why

    M270 Timing Chain Cold-Start Rattle (W246)

    Identical to the well-documented W176 A-Class fault: the M270 1.6T and M274 2.0T engines in the W246 B-Class share the same oil-pressure-dependent hydraulic tensioner design. Cold-start rattle is a widespread and documented issue across the B180, B200, and B250 petrol range. Chain tensioner failure can result in chain jump and engine damage if not addressed.

    What you would notice

    • Metallic rattle on cold start from front of engine, lasting more than 1–2 seconds
    • P0016/P0017 cam-to-crank correlation fault codes
    • Rough cold idle that settles once oil pressure builds
    • Rattle returns after extended cold soak

    Typically $2,000–$4,500 to put right.

  • Costly issue

    Test at low speed in a carpark — multiple slow pull-aways on light throttle.

    See why

    7G-DCT Dual-Clutch Shudder at Low Speed (W246)

    The W246 B-Class shares the same 7G-DCT dual-clutch transmission as the W176 A-Class. Low-speed shudder and judder when pulling away, parking, or creeping in traffic is a well-documented fault across both model lines. The B-Class application is particularly reported due to the heavier body and family-car urban driving pattern that stresses the dual-clutch at low speed more frequently.

    What you would notice

    • Shudder or vibration pulling away from rest on light throttle
    • Judder in slow-moving traffic
    • Hesitation or clunk when moving off from a standstill
    • Intermittent harsh gear changes

    Typically $900–$4,000 to put right.

  • Costly issue

    Insist on a genuine cold start - car not run that morning.

    See why

    M270 timing chain stretch on cold start (W246)

    The 1.6 and 2.0 turbo M270 petrol engines stretch the timing chain and wear the tensioner from roughly 80,000 km, particularly on early build cars. The tell-tale is a metallic rattle for several seconds on cold start that fades as oil pressure builds. Catch it early with a chain kit; ignore it and a slipped chain can bend valves.

    What you would notice

    • Metallic rattle for several seconds on cold start-up
    • Rough idle or misfire
    • Camshaft/crankshaft correlation fault codes

    Typically $1,800–$3,500 to put right.

  • Costly issue

    Ask the seller not to start the car before you arrive so you hear a genuine cold start.

    See why

    M266 timing chain stretch and rattle (W245)

    The M266 four-cylinder petrol in the W245 stretches its timing chain and wears the tensioner and guides, typically from around 80,000-120,000 km. You hear a metallic rattle for a second or two on cold start-up. If ignored the chain can eventually jump a tooth and cause valve-to-piston contact and serious engine damage, so a rattly example needs the chain, tensioner and guides done as a set.

    What you would notice

    • Metallic rattle or chatter for 1-3 seconds on cold start
    • Rough idle or occasional misfire
    • Check-engine light with camshaft/crankshaft correlation codes

    Typically $1,500–$3,200 to put right.

  • Costly issue

    Test at 80–100 km/h on a smooth road surface and listen for a cyclic hum or whine from the rear.

    See why

    B250e Electric Drive Motor Bearing Noise

    The B250e electric variant of the W246 B-Class uses a Tesla-sourced electric motor mounted at the rear. Bearing wear in the electric drive motor produces a cyclic whine or rumble that increases with road speed. Affected units produce noise at highway speeds that is initially mistaken for tyre or wheel bearing noise. Drive motor bearing replacement requires specialist equipment and is costly.

    What you would notice

    • Cyclic whine or rumble from rear of vehicle at highway speed
    • Noise increases proportionally with vehicle speed, not engine speed
    • Noise present under light load and regenerative braking
    • Sometimes confused with rear wheel bearing or tyre noise

    Typically $1,800–$5,000 to put right.

See all 8 documented issuesEverything researched for the Mercedes-Benz B-Class, including 1 rated critical.
Depends on which engine this Mercedes-Benz B-Class has — 8Each of these is documented for one particular engine. Pick the year and engine above to see which of them apply.
Engine, transmission & cooling7

01Autotronic CVT (722.8) shudder, jerking and failure (W245)

Test drive from cold and again after 15-20 minutes.petrol2005–2011TransmissionRead the full fault: symptoms, where to look, what to ask the seller

02B250e Electric Drive Motor Bearing Noise

Test at 80–100 km/h on a smooth road surface and listen for a cyclic hum or whine from the rear.ev2014–2017Engine
OccasionalEngine $1,800–$5,000 to fix

Can't confirm for this car

The B250e electric variant of the W246 B-Class uses a Tesla-sourced electric motor mounted at the rear. Bearing wear in the electric drive motor produces a cyclic whine or rumble that increases with road speed. Affected units produce noise at highway speeds that is initially mistaken for tyre or wheel bearing noise. Drive motor bearing replacement requires specialist equipment and is costly.

Symptoms to notice

  • Cyclic whine or rumble from rear of vehicle at highway speed
  • Noise increases proportionally with vehicle speed, not engine speed
  • Noise present under light load and regenerative braking
  • Sometimes confused with rear wheel bearing or tyre noise

What to check

  1. Test at 80–100 km/h on a smooth road surface and listen for a cyclic hum or whine from the rear.
  2. Swap test — swap rear tyres to eliminate tyre noise as a source.
  3. Check for any drivetrain warning codes in the EV control module.
  4. Verify the motor has not already had a bearing replacement and check for any service bulletins from Mercedes-Benz or Tesla (as motor supplier) related to the B250e drivetrain.

Where to look: Rear-mounted electric drive motor, underneath rear boot floor

Parts involved: Wheel bearing.

Ask the seller

  • “Has the rear electric motor or drive unit been inspected?”
  • “Is there any noise from the rear at highway speeds?”
  • “Has the car had any drivetrain warning lights or codes?”

03M270 Timing Chain Cold-Start Rattle (W246)

Perform a cold-start test — listen for chain rattle in the first 5 seconds.petrol2011–2018Engine
Very commonEngine $2,000–$4,500 to fix

Can't confirm for this car

Identical to the well-documented W176 A-Class fault: the M270 1.6T and M274 2.0T engines in the W246 B-Class share the same oil-pressure-dependent hydraulic tensioner design. Cold-start rattle is a widespread and documented issue across the B180, B200, and B250 petrol range. Chain tensioner failure can result in chain jump and engine damage if not addressed.

The front of a dual overhead camshaft engine with the timing cover removed, exposing the timing chain and sprockets.Example of the part — not this vehicle

The front of a twin-cam engine with the timing cover off — chain, sprockets and guides.

Logansenf · CC BY-SA 4.0 · Wikimedia Commons

Symptoms to notice

  • Metallic rattle on cold start from front of engine, lasting more than 1–2 seconds
  • P0016/P0017 cam-to-crank correlation fault codes
  • Rough cold idle that settles once oil pressure builds
  • Rattle returns after extended cold soak

What to check

Perform a cold-start test — listen for chain rattle in the first 5 seconds. Any sustained rattle beyond a brief tick is abnormal. Inspect oil service records for interval compliance. The B-Class attracts older buyers who may have used extended-interval servicing, compounding this risk. If a workshop inspection is possible: Scan OBD system for timing-related fault codes.

Where to look: Front left of engine bay, timing chain cover

Parts involved: Timing chain.

Ask the seller

  • “Has the timing chain or tensioner been replaced or inspected?”
  • “What has the oil change interval been and which oil grade?”
  • “Has a rattle ever been noticed on cold starts?”

047G-DCT Dual-Clutch Shudder at Low Speed (W246)

Test at low speed in a carpark — multiple slow pull-aways on light throttle.petrol2011–2018Transmission
CommonTransmission $900–$4,000 to fix

Can't confirm for this car

The W246 B-Class shares the same 7G-DCT dual-clutch transmission as the W176 A-Class. Low-speed shudder and judder when pulling away, parking, or creeping in traffic is a well-documented fault across both model lines. The B-Class application is particularly reported due to the heavier body and family-car urban driving pattern that stresses the dual-clutch at low speed more frequently.

Symptoms to notice

  • Shudder or vibration pulling away from rest on light throttle
  • Judder in slow-moving traffic
  • Hesitation or clunk when moving off from a standstill
  • Intermittent harsh gear changes

What to check

  1. Test at low speed in a carpark — multiple slow pull-aways on light throttle.
  2. Any vibration or shudder through the driveline indicates clutch pack wear or fluid degradation.
  3. Check transmission fluid service record (often skipped on B-Class as family/elderly owner car).
  4. Verify whether the transmission ECU software has been updated by Mercedes-Benz.

Where to look: Transmission unit, central under bonnet, wet dual-clutch housing

Parts involved: Clutch.

Ask the seller

  • “Has the dual-clutch fluid been serviced?”
  • “Has the car ever had a shudder or vibration when pulling away?”
  • “Has the transmission had any dealer software updates?”

05M270 timing chain stretch on cold start (W246)

Insist on a genuine cold start - car not run that morning.petrol2012–2019Engine
CommonEngine $1,800–$3,500 to fix

Can't confirm for this car

The 1.6 and 2.0 turbo M270 petrol engines stretch the timing chain and wear the tensioner from roughly 80,000 km, particularly on early build cars. The tell-tale is a metallic rattle for several seconds on cold start that fades as oil pressure builds. Catch it early with a chain kit; ignore it and a slipped chain can bend valves.

The front of a dual overhead camshaft engine with the timing cover removed, exposing the timing chain and sprockets.Example of the part — not this vehicle

The front of a twin-cam engine with the timing cover off — chain, sprockets and guides.

Logansenf · CC BY-SA 4.0 · Wikimedia Commons

Symptoms to notice

  • Metallic rattle for several seconds on cold start-up
  • Rough idle or misfire
  • Camshaft/crankshaft correlation fault codes

What to check

  1. Insist on a genuine cold start - car not run that morning.
  2. Listen at the front of the engine for a rattle that disappears after a second or two.
  3. Ask whether the chain has already been replaced, and at what kilometres.

Where to look: Front of the engine behind the timing cover

Parts involved: Timing chain.

Ask the seller

  • “Has the timing chain and tensioner been done?”
  • “Any rattle on the first start of the day?”

06M266 timing chain stretch and rattle (W245)

Ask the seller not to start the car before you arrive so you hear a genuine cold start.petrol2005–2011Engine
CommonEngine $1,500–$3,200 to fix

Can't confirm for this car

The M266 four-cylinder petrol in the W245 stretches its timing chain and wears the tensioner and guides, typically from around 80,000-120,000 km. You hear a metallic rattle for a second or two on cold start-up. If ignored the chain can eventually jump a tooth and cause valve-to-piston contact and serious engine damage, so a rattly example needs the chain, tensioner and guides done as a set.

The front of a dual overhead camshaft engine with the timing cover removed, exposing the timing chain and sprockets.Example of the part — not this vehicle

The front of a twin-cam engine with the timing cover off — chain, sprockets and guides.

Logansenf · CC BY-SA 4.0 · Wikimedia Commons

Symptoms to notice

  • Metallic rattle or chatter for 1-3 seconds on cold start
  • Rough idle or occasional misfire
  • Check-engine light with camshaft/crankshaft correlation codes

What to check

Ask the seller not to start the car before you arrive so you hear a genuine cold start. Stand at the front of the engine bay as it fires and listen for a rattle that fades once oil pressure builds. A short, sharp rattle every cold start is the warning sign.

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

Parts involved: Timing chain.

Ask the seller

  • “Has the timing chain, tensioner and guides ever been replaced?”
  • “Is there any rattle on the first cold start of the day?”

07Thermostat housing and coolant leaks (W246)

The M270's plastic thermostat housing warps and its seals harden, weeping coolant and sometimes tripping temperature warnings or fault codes.petrol2012–2019Cooling
CommonCooling $450–$1,200 to fix

Can't confirm for this car

The M270's plastic thermostat housing warps and its seals harden, weeping coolant and sometimes tripping temperature warnings or fault codes. It is a common age-related job on these engines. Cheap enough as a standalone fix but worth spotting so you can negotiate.

An annotated photograph of an automotive engine thermostat identifying the wax capsule and both disc valves.Example of the part — not this vehicle

A double-valve engine thermostat, labelled: the wax capsule is what sticks.

Dougsim · CC BY-SA 3.0 · Wikimedia Commons

Symptoms to notice

  • Sweet coolant smell after a drive
  • Slowly dropping coolant level
  • Temperature gauge fluctuating or a coolant warning

What to check

With the engine cold, check the coolant reservoir level and look for crusty pink/orange residue around the thermostat housing at the front of the engine. After the test drive, sniff for a sweet coolant smell and check for drips under the front.

Where to look: Thermostat housing at the front of the engine block

Parts involved: Thermostat.

Ask the seller

  • “Has the thermostat housing ever leaked or been replaced?”
  • “Does the coolant level need topping up?”
Body, brakes, suspension & interior1

01Front suspension knock and premature wear (W245)

On the test drive, cross a rough patch or driveway lip at low speed and listen for knocking from the front.petrol2005–2011Suspension
CommonSuspension $400–$1,400 to fix

Can't confirm for this car

The tall, city-driven W245 wears front suspension bushes, drop links and lower arm ball joints faster than owners expect, producing knocking and rattling over bumps. It is not catastrophic but it fails NZ WoF checks and adds up if several parts need doing at once. Worth budgeting for on any high-kilometre example.

Symptoms to notice

  • Knock or clunk over bumps and speed humps
  • Rattle from the front on rough roads
  • Uneven front tyre wear

What to check

On the test drive, cross a rough patch or driveway lip at low speed and listen for knocking from the front. Grab each front tyre top-and-bottom and rock it for play. Check the front tyres for uneven or feathered wear.

Where to look: Front suspension - control arm bushes, ball joints and anti-roll bar drop links

Parts involved: Ball joint.

Ask the seller

  • “Have any front suspension bushes or links been replaced recently?”
  • “Does it knock over bumps?”

Mercedes-Benz B-Class faults in detail

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.

Autotronic CVT (722.8) shudder, jerking and failure (W245)Critical · Transmission

What these repairs cost on other cars

Some of the Mercedes-Benz B-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 faultsMercedes-Benz A-Class23 documented faultsMercedes-Benz E-Class23 documented faultsMercedes-Benz GLB8 documented faultsMercedes-Benz GLE7 documented faultsMercedes-Benz ML5006 documented faults

Mercedes-Benz B-Class buyer questions

Is the Mercedes-Benz B-Class reliable?

Like any used car, it depends on the specific example and its service history. Across the 8 documented faults for the Mercedes-Benz B-Class, the recurring problem areas are transmission, engine, and suspension. A Mercedes-Benz B-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 B-Class?

We've catalogued 8 known faults for the Mercedes-Benz B-Class, covering transmission, engine, and suspension. All 8 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 B-Class?

Most single repairs on the Mercedes-Benz B-Class fall between $1,500–$3,500 at NZ independent-workshop rates. Some of the 8 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 B-Class?

Yes. A Mercedes-Benz B-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.