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Mercedes-Benz2011–2017 Critical issues documented

Mercedes-Benz CLS: common faults & what to check

Thinking about buying a used Mercedes-Benz CLS (2011–2017) in New Zealand? We've documented 5 known faults for this model spanning engine, transmission, and fluid leaks. 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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5

Documented faults

Critical

Most serious

$1,800–$4,500

Typical repair

3

Systems covered

Which Mercedes-Benz CLS are you looking at?

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

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Mercedes-Benz CLS

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Can't confirm for this car

Mercedes-Benz CLS

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 CLS before you hand over any money. Every documented fault is listed below, each with its own page.

  • Serious issue

    Ask the seller not to start the car before you arrive and put your hand on the bonnet to confirm it is cold.

    See why

    Intake camshaft adjuster failure and timing chain tensioner cold-start rattle (M276 3.5 V6, CLS350)

    The M276 3.5 V6 in the CLS350 has two related timing faults. Oil drains back out of the chain tensioners after the car sits, so the chains go slack for a few seconds on a cold start and rattle, and the locking pins inside the intake camshaft adjusters (variable valve timing sprockets) wear until the adjuster jumps, setting cam timing codes such as P002177 or P001885. Early engines (Mercedes lists serial numbers up to roughly 276 8xx 30 000790, so most 2011-2012 CLS350s) are the most affected; Mercedes answered with a technical service bulletin for the rattle after start that adds oil check valves to the tensioner feeds and fits revised tensioners, and that is not a free recall. Left alone, repeated dry starts wear the chain, guides and adjusters, and a slipped adjuster can cause rough running, limp mode or, in the worst case, valve and piston contact.

    What you would notice

    • Metallic rattle or grinding from the front of the engine for 2 to 5 seconds after a cold start
    • Check engine light that comes and goes
    • Rough idle or hesitation, worse when cold
    • Longer than normal cranking before it fires
    • Clunk from the front of the engine on start-up

    Typically $2,800–$8,500 to put right.

  • Costly issue

    On the test drive, drive for at least 20 minutes so the gearbox is fully hot, as these faults often only appear warm.

    See why

    7G-Tronic Plus 722.9 conductor plate (transmission control unit) failure, stuck in limp mode

    Every CLS with the 7G-Tronic Plus 722.9 gearbox has its transmission control unit and speed sensors built onto a conductor plate inside the gearbox, sitting in hot fluid. The speed sensors (Y3/8n1, n2, n3) or the board fail, the gearbox loses its speed signals and drops into limp mode, holding 2nd gear (or no reverse) until the engine is restarted, and the fault usually gets more frequent until the plate is replaced and coded online to the car. Old fluid also wears the valve body, giving harsh or flared shifts. Some facelift diesels (2014 on) moved to the 9G-Tronic, which does not share this part.

    What you would notice

    • Gearbox stuck in 2nd gear with a transmission warning, back to normal after a restart
    • Harsh or thumping downshifts coming to a stop
    • Flare or slip on the 2-3 or 3-4 change
    • Delayed engagement when selecting Drive or Reverse
    • Speedometer or cruise control dropping out at the same time as a shift fault

    Typically $1,800–$4,500 to put right.

See all 5 documented issuesEverything researched for the Mercedes-Benz CLS, including 1 rated critical.
Depends on which engine this Mercedes-Benz CLS has — 5Each of these is documented for one particular engine. Pick the year and engine above to see which of them apply.
Engine, transmission & cooling3

01Intake camshaft adjuster failure and timing chain tensioner cold-start rattle (M276 3.5 V6, CLS350)

Ask the seller not to start the car before you arrive and put your hand on the bonnet to confirm it is cold.petrol2011–2017EngineRead the full fault: symptoms, where to look, what to ask the seller

02Delphi piezo fuel injector failure (OM651 2.1 diesel, early CLS250 CDI)

diesel2011–2012Engine
OccasionalEngine $1,200–$5,500 to fix

Can't confirm for this car

Early OM651 2.1 four-cylinder diesels, including the CLS250 CDI, were built with Delphi piezo injectors that fail or leak, causing rough running, limp mode and cut-outs, and a leaking injector can in rare cases damage a piston. Mercedes ran a worldwide service measure (not called a recall) on about 300,000 OM651 engines, first swapping in updated piezo injectors and later replacing them with solenoid injectors; the factory changeover to solenoid injectors happened during 2012. Cars that missed the measure, or had only some injectors replaced, are the risk, and Mercedes no longer does this work free on cars this old.

A single common-rail diesel fuel injector photographed against a plain background.Example of the part — not this vehicle

A common-rail diesel injector. Contamination damages the nozzle at the tip.

Panoha · CC BY-SA 3.0 · Wikimedia Commons

Symptoms to notice

  • Engine warning light and limp mode with loss of power
  • Rough running, judder or misfire, especially at idle
  • Engine cutting out while driving
  • Hard starting or a diesel knock that was not there before

What to check

  1. Start the engine and listen at idle for uneven running or a lumpy, shaking idle, then on the test drive accelerate firmly through the gears and check for hesitation, judder or a limp mode warning.
  2. Open the bonnet and, with the engine cover lifted if it pulls off by hand, use a phone torch to check whether the injectors have small return pipes connected to them: the updated solenoid injectors do and the original piezo ones do not.
  3. Ask for paperwork showing the injector service measure was carried out and look for the sticker on the camshaft cover with injector codes crossed out by the dealer.
  4. If a workshop inspection is possible: have the injector quantity correction values read with a Mercedes-capable scan tool and a return-flow (leak-off) test done.

Where to look: Top of the engine under the plastic engine cover, one injector per cylinder

Parts involved: Fuel injector.

Ask the seller

  • “Has the injector service measure been done by a Mercedes dealer?”
  • “Were all four injectors replaced or only some?”
  • “Has the car ever gone into limp mode or cut out?”

037G-Tronic Plus 722.9 conductor plate (transmission control unit) failure, stuck in limp mode

On the test drive, drive for at least 20 minutes so the gearbox is fully hot, as these faults often only appear warm.2011–2017TransmissionRead the full fault: symptoms, where to look, what to ask the seller
Fluid leaks2

01Oil cooler seal leak in the engine valley (OM642 3.0 V6 diesel, CLS350 CDI / BlueTEC)

The OM642 3.0 V6 diesel has its oil cooler buried in the valley between the cylinder banks, sealed by rubber seals that harden and leak.diesel2011–2017Fluid LeaksRead the full fault: symptoms, where to look, what to ask the seller

02Upper timing cover and camshaft cover oil leaks (M276 3.5 V6, CLS350)

petrol2011–2017Fluid LeaksRead the full fault: symptoms, where to look, what to ask the seller

Mercedes-Benz CLS 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.

7G-Tronic Plus 722.9 conductor plate (transmission control unit) failure, stuck in limp modeMajor · TransmissionIntake camshaft adjuster failure and timing chain tensioner cold-start rattle (M276 3.5 V6, CLS350)Critical · EngineOil cooler seal leak in the engine valley (OM642 3.0 V6 diesel, CLS350 CDI / BlueTEC)Major · Fluid LeaksUpper timing cover and camshaft cover oil leaks (M276 3.5 V6, CLS350)Major · Fluid Leaks

What these repairs cost on other cars

Some of the Mercedes-Benz CLS’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 GL-Class5 documented faultsMercedes-Benz W1635 documented faultsMercedes-Benz GLA21 documented faults

Mercedes-Benz CLS buyer questions

Is the Mercedes-Benz CLS reliable?

Like any used car, it depends on the specific example and its service history. Across the 5 documented faults for the Mercedes-Benz CLS, the recurring problem areas are engine, transmission, and fluid leaks. A Mercedes-Benz CLS 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 CLS?

We've catalogued 5 known faults for the Mercedes-Benz CLS, covering engine, transmission, and fluid leaks. All 5 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 CLS?

Most single repairs on the Mercedes-Benz CLS fall between $1,800–$4,500 at NZ independent-workshop rates. Some of the 5 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 CLS?

Yes. A Mercedes-Benz CLS 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.