Fault File
All models / All cars / Family hatchbacks / Mercedes A-Class

Mercedes A-Class

All generations and engines together · 326,126 MOT tests in the 2025 data · typical mileage at age 7: 61k

First-time failure at age 7
20.1%
Across 38,366 tests. The average across all tracked models is 19.5%.
Rank at age 7
149 of 239
1 = lowest failure rate among the models tracked.
Typical mileage at age 7
61k miles
Check the mileage view below; low-mileage models can look better by age than they are.

Generation

Split by first-registration year. Cars registered in a changeover year can belong to either generation.

How this model wears

Mercedes A-ClassClass average, all tracked models

Known issues

Measured

Computed from DVSA MOT results, all of Great Britain, 2025. Nothing here is opinion.

What testers flag

Share of tests where each item was recorded. The dark tick is the class average across all tracked models; bars are scaled within each group.

Faults with the car itself

The rows that judge the model rather than its keeper. 155,859 tests in this band.

A suspension joint dust cover severely deteriorated
Minor
3.1%class 1.1%
A spring or spring component fractured or seriously weakened
Fail
3.0%class 1.4%
A suspension pin, bush or joint excessively worn
Advisory
1.9%class 0.9%
A suspension joint dust cover missing or no longer prevents the ingress of dirt etc
Fail
1.7%class 0.6%
Brake pipe damaged or excessively corroded
Advisory
1.4%class 1.9%
An SRS malfunction indicator lamp (MIL) indicates a system malfunction
Fail
1.4%class 0.2%
A wheel badly distorted or wear between wheel and hub at spigot mounting
Advisory
1.3%class 0.6%
Engine MIL illuminated indicating a malfunction
Fail
1.1%class 0.4%
Fluid leaking excessively and likely to harm the environment or to pose a safety risk to other road users
Advisory
1.0%class 2.0%

Wear, upkeep and luck

Tyres, pads and stone chips say more about how the car was driven and maintained than about how it was built.

Tyre tread depth not in accordance with the requirements
Advisory
29.2%class 22.9%
A tyre seriously damaged
Advisory
16.2%class 13.4%
A brake lining or pad worn below 1.5mm
Advisory
11.3%class 8.7%
Brake disc or drum excessively weakened, insecure or fractured
Advisory
11.2%class 10.1%
Brake disc or drum significantly and obviously worn
Advisory
6.4%class 3.4%
Tyre tread depth not in accordance with the requirements
Fail
3.4%class 2.2%
A brake lining or pad worn below 1.5mm
Fail
2.3%class 1.6%
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
Minor
2.1%class 2.0%

Unconfirmed issues

Reported

Owner folklore from forums and the motoring press. Most of it never shows up in an MOT, which is why this section exists at all.

Blank or black instrument cluster

Emerging

On W177 cars (2018 on) the digital driver display behind the wheel can go completely black, sometimes clearing itself after a software update, sometimes needing the LVDS cable or connector behind the dash replaced. It has turned up on cars only a few thousand miles old and can come back. Mercedes has issued a formal recall for the same kind of MBUX display fault on later C-Class, E-Class and GLC models, but nothing confirmed for the A-Class itself, so a dealer denying any known issue is worth pushing back on.

Reported from new to a few years old · sources: Honest John owner reviews, aclassclub.co.uk forum, Carscoops

Timing chain rattle on petrol turbo engines

Emerging

The M270 1.6 and 2.0-litre turbo petrol engines (A180, A200, A250, W176) can develop a rattly cold start as the timing chain stretches and the plastic guides wear, usually from around 50,000 to 80,000 miles and worse on cars used mainly for short urban runs. Because the engine sits transversely, a full chain, guide and tensioner kit is a labour-heavy job, and independent specialists quote roughly £1,400-£2,000. No confirmed manufacturer recall covers this specific wear pattern on the A-Class.

Reported 50-80k miles · sources: mercedes-specialist.uk, aclassclub.co.uk forum, independent Mercedes specialist write-ups

7G-DCT judder, slip and mechatronics wear

Automatics only

Cars fitted with the 7G-DCT dual-clutch automatic (W176, roughly 2013-2020) can develop hesitation, jerky take-up from a stop, and occasional 'reverse not available' warnings as the clutch packs and mechatronic unit wear. It tends to show up from about 70,000 miles, and gearbox specialists quote roughly £900-£2,000 for clutch pack work or £1,200-£3,000 if the mechatronic unit needs replacing. Manuals and the later 9G-Tronic automatic are not affected by this particular gearbox's faults.

Reported from 70k miles · sources: aclassclub.co.uk forum, ASR Gearbox Repairs, benzworld.org

DPF struggling to regenerate on diesel

Diesel only

Diesel A-Classes used mainly for short journeys often can't get the DPF hot enough to self-clean, leading to warning lights, a real-world mpg drop, and on some cars diesel getting past the injectors into the sump during failed regeneration attempts, raising the oil level. It's a diesel-specific, mostly usage-pattern problem rather than a build defect, and it has cropped up on both the older W169 and the later W176/W177 diesels.

Reported across diesel models, mainly short-trip cars · sources: Honest John carbycar, mercedes-specialist.uk, WhoCanFixMyCar

Flooded rear footwell or spare wheel well

Emerging

On W176 cars a pressure-equalisation vent flap between the rear load area and the bumper can fail or clog, letting water into the boot floor and rear footwells. Owners have reported soaked carpets and damp electrics on cars from a few years old up to over six years old, with Honest John's owner reports listing repair quotes of roughly £790-£1,500 to fix the flap and dry the car out. It's not something a routine MOT check will pick up.

Reported on 2013-2020 cars · sources: Honest John carbycar, aclassclub.co.uk forum

Discs warping, judder coming back after replacement

Partly in the MOT data

Owners across both W176 and W177 report brake judder returning within a few thousand miles of fitting new discs and pads, in some cases three sets within a year, usually put down to hot-spotting from heavy braking or use of the brake-hold function rather than a parts defect. This lines up with brakes being the measured signature MOT fault for this segment: the folklore matches the data, though forum posters mostly blame driving style and fitment rather than the discs themselves.

Reported across generations · sources: aclassclub.co.uk forum brake judder threads, Honest John carbycar (W169 disc wear reports)

Viewing one? Ask this

Built from the two sections above.

Start the car stone cold and listen for a rattle from the front of the engine for the first few seconds. A metallic rattle that fades as revs rise points to timing chain and tensioner wear, worse on higher-mileage petrol turbo cars.
On an automatic, pull away from rest a few times and try reverse. Hesitation, a jolt, or a 'reverse not available' message points to 7G-DCT clutch pack or mechatronic wear.
Check the digital instrument screen lights up instantly and stays on for the whole test drive. Any flicker or blackout of the driver display is the known instrument cluster fault.
Lift the boot floor and rear footwell mats and feel for damp or a musty smell. Wet carpet or a mouldy smell means the rear vent flap has let water in.
Brake firmly from speed a few times on a clear road and feel for vibration through the pedal or wheel. Judder means warped discs, and if it's come back soon after a recent replacement it's the pattern this model is known for.
On a diesel, check the dash for DPF or AdBlue warnings and ask what the car is normally used for. A car used mostly for short trips is more likely to have DPF clogging or AdBlue sensor problems.
Check the service history for oil changes at the right intervals with the correct-spec oil. Stretched service intervals speed up both timing chain wear and DPF/oil-dilution problems.

Others in its class

Same segment (Family hatchbacks), best MOT record first. Compare before you shortlist.

How it compares

Head to head with the other popular cars in its class on reliability and common faults.