What goes wrong, what it costs, and what to check before you buy a used Mercedes A Class.
The Mercedes A Class occupies a niche position on the UK market.
We track 9 known issues across the Mercedes A Class range, including 2 rated as safety-critical. Knowing which variants and configurations to approach with caution can save you from expensive surprises after purchase.
Found a Mercedes A Class? Enter the reg to see which of our 9 known issues apply to that exact car, plus full MOT history and mileage checks.
W169 (2004–2012) — Petrol options included the 1.5 A150, 1.7 A170, 2.0 A200, with 1.5 CDI, 2.0 CDI on the diesel side. Our database flags 3 known issues on this generation, 1 of which are rated as safety-critical. The most significant concern is CVT gearbox failure (£2,000–£3,500 to address).
W176 (2012–2018) — Petrol options included the 1.6 A160/A180, 2.0 A250, 2.0 A45 AMG, with 1.5 CDI, 2.1 CDI on the diesel side. Our database flags 7 known issues on this generation, 1 of which are rated as safety-critical. The most significant concern is Brake pipe corrosion (£150–£400 to address).
W177 (2018–2024) — Petrol options included the 1.3 A160/A180, 2.0 A200/A250, 2.0 A35/A45 AMG, with 1.5 CDI, 2.0 CDI on the diesel side. Our database flags 3 known issues on this generation, 1 of which are rated as safety-critical. The most significant concern is Brake pipe corrosion (£150–£400 to address).
The Autotronic CVT transmission in W169 A-Class models has a documented history of premature failure, leading Mercedes to abandon CVT technology in subsequent generations. The steel belt and pulley system suffers from inadequate lubrication and heat management, causing the belt to stretch or snap without warning. This results in complete loss of drive and typically requires full transmission replacement as repair is not economically viable. Mercedes initially claimed lifetime transmission fluid but later revised service requirements after widespread failures.
CVT failure results in complete loss of drive, leaving the car immobile and requiring recovery. Replacement with a remanufactured unit typically costs £2,000-£4,000 plus fitting. Used CVTs are available but carry the same inherent reliability issues. Many owners choose to scrap cars rather than repair due to the cost versus vehicle value.
Test the automatic gearbox extensively in slow traffic, car parks and on hill starts. Feel for any juddering, hesitation or clunking during gear changes. Try repeated low-speed manoeuvres as this is where problems are most apparent.
MOT data shows A-Class models with 1.5-litre petrol engines fail brake pipe corrosion tests at 3.5 times the national fleet average, particularly affecting cars aged 8-12 years. The brake pipes run close to road salt spray areas and use steel construction that is vulnerable to UK winter road salt corrosion. This is a safety-critical issue that can result in brake system failure and MOT failure. The problem appears to be generation-specific rather than affecting all A-Class variants equally.
Brake pipe failure results in complete loss of braking capability and represents an immediate danger to vehicle occupants and other road users. The car becomes illegal to drive and will fail MOT testing. Brake pipe replacement typically requires professional repair and system bleeding.
Check brake disc condition for lipping or scoring. Test braking at moderate speed for pulling to one side or vibration through the steering wheel. Review MOT advisories for brake-related items.
Turbocharger failure affects both diesel OM640 engines in W169 and high-performance M133 engines in W176 models, though for different reasons. The OM640 diesel suffers from oil feed pipe restrictions and carbon buildup in the variable vane mechanism, while the M133 AMG engine experiences bearing failure due to extreme operating temperatures and aggressive driving cycles. Both scenarios result in loss of boost pressure, reduced performance, and potential engine damage if driven hard with a failing turbo.
Failed turbo seals allow oil into the combustion chambers, causing blue smoke and potential engine damage from oil starvation. Complete turbo failure results in severe loss of power and possible engine failure if driven hard. Replacement requires turbo removal and oil system flushing to prevent contamination of the new unit.
During a test drive, check for hesitation, lack of power or unusual whining from the turbo area. Watch for blue or white smoke from the exhaust under hard acceleration. Check the oil condition and service history — turbos rely on clean oil.
The M270 1.6-litre turbocharged engine uses a timing chain system prone to premature stretch and tensioner failure. The chain tensioner hydraulic mechanism fails to maintain adequate tension, causing timing chain rattle particularly noticeable on cold starts. If left untreated, the chain can jump teeth or snap, resulting in valve-to-piston contact and catastrophic engine damage. This issue primarily affects early production engines and has been partly addressed in later revisions with updated tensioner designs.
Progressive timing chain stretch causes valve timing to retard, reducing performance and fuel economy. Complete chain failure results in valve-to-piston contact, requiring cylinder head removal and typically £3,000-£5,000 in engine rebuild costs. The car should not be driven if persistent timing chain rattle is present.
Listen carefully for a rattle or ticking noise from the engine on cold start — this is the most common early sign. Ask for evidence of chain replacement in the service history. On higher-mileage cars without documented replacement, budget for preventative work.
The A45 AMG with M133 engine suffers from premature clutch wear due to the high torque output (up to 500Nm in later models) and aggressive dual-clutch calibration. The AMG 7-speed DCT transmission subjects the clutch packs to extreme thermal stress, particularly during launch control use and track driving. Clutch pack failure typically manifests as slipping under full acceleration and requires transmission-out repair. This issue is exacerbated by enthusiastic driving and is particularly common on cars with documented track use.
Failed clutch packs cause loss of drive in affected gears, initially under high load but progressing to complete failure. Replacement requires transmission removal and typically costs £1,500-£3,000. The car becomes undriveable once clutch failure is complete.
Check each gear engages smoothly without crunching. Feel the clutch bite point — very high or very low can indicate wear. Listen for bearing noise when the clutch is depressed.
For the full breakdown of all 9 tracked issues with repair costs, see the Mercedes A Class common problems page.
Routine servicing (oil and filter change every 15k miles) typically costs £120–£180 at an independent garage.
The bigger-ticket items to budget for include dct fluid change (£300–£450), cvt fluid change (£250–£400), fuel filter (£200–£300).
See the full Mercedes A Class service schedule for every interval and cost breakdown.
The Mercedes A Class has some well-documented weak points, including 2 safety-critical issues that demand careful checking. The right example, properly maintained, can still be a sound purchase — but cutting corners on the pre-purchase inspection is not advisable.
Before committing, check the car's full MOT history, verify the service record is complete, and if possible arrange a specialist inspection. Enter any registration into our free report to see the complete picture.
Get Car Wise maintains a database of known mechanical issues for every popular car on UK roads, tracking the faults that owners, specialists and DVSA data reveal.
When you run a report on a specific Mercedes A Class, we cross-reference the exact variant, engine and age against our database of 9 known issues. Combined with full MOT history analysis, mileage verification and DVLA data, you get a complete picture before viewing.
Enter the registration for MOT history, mileage verification, known faults for that exact variant, and a Get Car Wise Score.
This guide was compiled from independent expert reviews, DVSA MOT data, specialist workshops and our own database of 9 known Mercedes A Class issues. We are not affiliated with any source listed.