Used Mercedes C-Class 2014-2021 reliability

A prestige brand image isn’t always an indicator of superior quality, as the data for the Mercedes C-Class shows in our reliability survey, with nearly a third of cars presenting a problem.

This list of faults reported have been numerous, so you'll need to check everything. Try all the electrical items work while you poke around the interior, try the sat nav and make sure the air-con blows cold air and that there are no weird smells. During your test drive, listen out for any interior rattles; pay attention to the gearbox and that it operates smoothly and that there are no nasty knocks and bangs from the suspension over bumps.

Check also that the car doesn't pull heavily to one side as you're driving down the road, and that it also doesn't deviate under braking. The engine should have a smooth power delivery and not have any flat-spots or surges of acceleration. On automatic versions, make sure the kick-down function works under full acceleration - when it is safe to do so.

Seatbelts

The switches used in the seatbelt buckles of some examples made between 1 June 2018 and 31 October 2018 could be faulty. Check with a Mercedes dealer to find out if this applies to your car because they'll need to fit new buckles if it does.

Incorrect engine undertray

The wrong engine undertray was fitted to some C-Class' built between 1 March 2018 and 31 March 2018, but this can easily be rectified by a Mercedes dealer who will check and replace it if necessary.

Front seat frame

The welds on the seat frames of the front AMG performance seats fitted to cars manufactured from 8 June 2017 and 2 June 2018 could fail during a collision. Find out from a Mercedes dealer if your car is affected because they will need to inspect the seats and repair them if found to be faulty.

Emissions software update

A number of C200d models fitted with the Renault-sourced 1.6-litre diesel engine and were made from 1 August 2014 to 31 May 2018 will need to have a software update performed by a Mercedes dealer to improve exhaust emissions, and have a supplementary booklet added alongside the owner's manual.

Engine stall

A software issue could lead to the start/stop function being disabled and cause the engine to stall. This issue can be rectified with an update that can be performed by a Mercedes dealer.

Tie rod

A small number of vehicles built between 6 February 2019 and 12 February 2019 might have incorrectly fitted tie rods on the front suspension. If your car is affected, it will need to be checked over by a dealer, who'll rectify the issue for you.

Cracked lock nut

A lock nut used in the steering gear of some models made from 1 March 2015 and 31 October 2018 could be cracked, and will need to be inspected and replaced by a Mercedes dealer.

Electronic Stability Program (ESP)

A certain number of cars made from 1 June 2017 to 30 November 2018 have a software issue with the electronic stability program (ESP) that will need to be reprogrammed by a Mercedes dealer to ensure it works as intended.

Crankshaft

The crankshaft fitted to a small number of engines installed in cars built from 1 February 2019 to 31 March 2019 could have surface damage that'll reduce its durability. Speak to a Mercedes dealer to find out if this applies to your car, because it will require a new engine if it does.

Engine wiring harness

A wiring harness in the engine bay might not have been installed correctly and any affected vehicles will need to have this checked out by a Mercedes dealer, who'll carry out any necessary repairs to prevent any future issues.

Front passenger airbag

There have been two recalls for the front passenger airbag. The first applies to C-Class models made between 1 August 2017 and 31 October 2018 regarding a software glitch that'll require an update at a dealer. The second is for a bad connector that could prevent the airbag from deploying in a collision on some pre-June 2018 cars.

Axle mounting

This applies to the high-performance AMG models made between 1 June 2014 and 31 May 2016 where the rear axle mountings could break under extreme circumstances, such as full acceleration on a wet surface or when repeatedly breaking traction of the rear wheels. If your car is affected, it'll need to have some software updates applied by a Mercedes dealer to the ESP and electronic chassis control units to limit performance during such scenarios.

Mounting bolts of the turbocharger oil return line

A small number of cars made from 1 December 2018 and 31 January 2019 that need to have the bolts that hold the turbocharger oil return lines in place replaced, but a Mercedes dealer will be able to inform you if your example is affected.

Power steering

There have been three recalls to the power steering of the C-Class. First is the motor itself that can fail on models built between 1 August 2014 and 31 December 2016 and will need to be replaced. Then there was a software problem on some cars built from 1 November 2017 and 30 April 2018 that require an update. Finally, there is a sensor issue in the system of examples manufactured between 1 July 2018 and 31 August 2018 that could fail. Speak to your Mercedes dealer who'll be able to say if any of these applies to your car.

Driver's airbag

There has been an issue found with the driver's airbag of some cars made from 1 January 2018 and 30 March 2018 where the bag itself won't perform as intended in a collision. Your dealer will be able to find out if this applies to your car.

Rear beltline trim

The rear beltline trim on the exterior of examples manufactured from 1 January 2016 and 30 November 2017 can come loose, and will need to be inspected at a Mercedes dealer to determine if it needs replacing.

Front seatbelt pre-tensioners

Both the left and right front seats of cars made between 1 April 2016 and 31 March 2017 have been found to be faulty, meaning that front seat occupants aren't restrained correctly in a collision. Find out from a dealer if yours is affected and have the pre-tensioners replaced.

Radar control unit

This software issue applies to cars made from 1 February 2017 and 31 July 2019 and affected cars will require an update to the radar control unit in order for all the various automatic safety systems to function correctly.

In our most recent reliability survey, the Mercedes C-Class finished eighth out of 24 cars in the executive car class. This is an improvement on its performance in recent years.

Reliability rating 93.0%

What went wrong? Non-engine electrics 11%, exhaust 6%, fuel system 4%, battery 3%, bodywork 3%, infotainment/sat-nav 3%, brakes 2%, steering 2%, engine 1%, gearbox/clutch 1%, interior trim 1%

A third of C-Classes went wrong, according to owners, who reported a wide range of issues. Faults rendered more than a third of cars undriveable, and one in four was off the road for more than a week. Although 81% of cars were fixed for free, a small percentage of owners paid out more than £1500 in repair bills.

Owner’s view “This is the worst car I have ever bought. Faults haven’t been properly fixed and the service from the dealer has been poor”

Mercedes as a brand finished in a disappointing 24th place out of 32 manufacturers in the same survey. Check out the full list of brands here.

Used Mercedes C-Class reliability: the owners' view

As part of our annual Reliability Survey, owners of the Mercedes C-Class told us that their cars were mostly proving reliable, with a good portion of owners highlighting that their cars remained dependable even after several years of use.

Of the readers who did experience faults, some mentioned that the car’s exhaust gas sensors could be prone to failure. And putting those sensors right could prove costly, especially on cars which had covered less than 50,000 miles.

Experience of Mercedes’ dealer network was varied, with some readers noting expensive servicing costs when using the brand’s own dealers. The cost of updating sat-nav maps, as well as consumable parts, was also noted.

If you would like to see the full reliability list, head to the What Car? Reliability Survey pages for more information.