Mercedes-Benz CLA Common Problems & Known Faults (UK)
If you are considering buying a used Mercedes-Benz CLA, there are several major reliability issues worth knowing about first. Our garage database tracks 3 known faults for this model, 2 of them rated high severity. Every one below is a repair bill a seller has good reason not to mention.
Are you about to buy a lemon?
Sellers rarely admit these faults outright. Our database tracks 8 specific phrases sellers use in adverts to soft-pedal these exact issues. Paste any Mercedes-Benz CLA advert and we will check it in seconds.
Timing chain stretch and leaking hydraulic tensioners on the M270 turbo petrol. The chain rattles on cold start as the tensioner loses oil pressure; left alone the plastic guides wear, the chain can skip a tooth and throw camshaft timing codes (P0016/P0017 family), and in the worst case the valves contact the pistons. The transverse installation in the A-Class makes the repair far more labour-intensive than on rear-drive Mercedes, so UK specialist quotes run 1400-2000 pounds
Rough guide
£1400-2500
Typical symptoms
metallic rattle from the engine for several seconds on cold start-up
engine management light with camshaft timing fault codes
rough running or misfire once the chain has jumped
Affected vehicles
Engines:
1.6 / 2.0 Turbo Petrol (M270)
Typical mileage:
50000-100000 miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
The 7G-DCT dual-clutch automatic suffers low-speed judder and jerky shifts as the wet clutch packs wear, and mechatronic (electrohydraulic control unit) failures that cause delayed engagement, harsh 2nd-3rd shifts, limp mode or loss of drive. Mechatronic replacement is quoted at 1200-1800 pounds by UK specialists; clutch pack replacement is similar. Neglected 40k-mile fluid changes accelerate both
Rough guide
£1200-2500
Typical symptoms
shuddering or juddering when pulling away from a stop
hesitation or a lurch when setting off, worse when cold
clunk into P, N or R, or harsh low-gear shifts
gearbox warning and limp mode in advanced cases
Affected vehicles
Engines:
All with 7G-DCT dual-clutch automatic (Getrag 724.0)
Typical mileage:
50000-100000 miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
A broken steering column spring, coupled with insufficiently earthed wiring, may lead to a short circuit and inadvertent deployment of the driver's airbag. This was subject to a voluntary recall by Mercedes-Benz.
Rough guide
£0 (free safety recall)
Typical symptoms
Airbag warning light appearing on the dashboard
Unexpected airbag deployment
Affected vehicles
Engines:
All variants
Typical mileage:
All mileages miles
🔍 We have a specific pre-purchase check for this faultCheck an advert →
Mercedes-Benz CLA service intervals: cambelt, chain and gearbox oil
An overdue cambelt is the most expensive thing a seller can fail to mention on a used CLA. These are the figures UK specialists work to.
Timing chainChain
M270, M274, 1.6 TURBO, W176, W246
No fixed replacement interval
Dual-stage chain system: an upper cam chain plus a lower oil-pump and balance-shaft chain. Cam phasers (Y49/1, Y49/2) wear from around 60,000-80,000 km giving a cold-start tick; chain and guide wear shows from about 80,000 km on urban short-trip cars but 120,000-140,000 km on motorway cars. A metallic cold-start rattle needs prompt attention. The M274 DE16 is the longitudinal C-Class version of the same 1.6.
Always confirm against the vehicle handbook. Intervals vary by engine, and several manufacturers revised theirs after failures in service.
Repair costs are typical UK ranges, not quotes. Actual cost depends on condition and garage.Data last verified: September 2026
Where this Mercedes-Benz CLA fault data comes from
If you used to check the Honest John “Good & Bad” section before the site closed in 2026, this page is where that information now lives. We rebuilt the Mercedes-Benz CLA owner-report history from the archived Honest John dataset, added our own research, specialist and owner-club sources and DVSA recall data, and we keep it free. Each fault above is badged with its source. The same data feeds our free advert check, which reads a listing against every known fault for the exact engine and year.
Knowing what a Mercedes-Benz CLA goes wrong with is half of it. The rest is reading the advert and checking the car's history before you hand any money over.