Models · Mercedes-Benz
Mercedes-AMG A35 and A45 S W177 buying guide
The second-generation AMG A-Class arrived in 2019 in two strengths: the A35, and the A45 S with the M139, a 421hp 2.0 litre four-cylinder. Both have four-wheel drive and a dual-clutch gearbox. The checks below are for the A45 S.
The versions
- A35: 2.0 litre turbocharged petrol, 302bhp, seven-speed dual-clutch gearbox, four-wheel drive
- A45 S: M139 2.0 litre turbocharged inline four (1,991cc), 421hp and 369lb ft (the non-S A45 wasn't sold in the UK)
- A45 S: eight-speed dual-clutch gearbox and 4Matic+ four-wheel drive with a rear differential that can send power to one rear wheel, plus Drift Mode
What to check on a W177 A35 or A45
3 model-specific things to look at when you view one. They're a starting point, not the full inspection.
Noises from the rear axle on the A45 S
What to look for: On the test drive, listen for unusual noises from the back of the car when pulling away, on and off the throttle, and over bumps. Ask a Mercedes dealer, with the registration or VIN, whether all recalls have been done.
Why it matters: In late 2024 the A45 S was recalled after owners reported unusual noises from the rear. The fix is a replacement flex disc in the driveline and a new shield, carried out by dealers, though parts were in short supply. Most cars should have had it by now, and the dealer can confirm it.
Suspension warning messages on the A45 S
What to look for: With the engine running and during the drive, watch the dashboard for a message such as 'suspension malfunction, do not exceed 50mph'. Ask whether it has ever appeared and what was done.
Why it matters: Some A45 S cars showed this warning, usually caused by a faulty ride level sensor rather than a fault in the dampers themselves. It can often be cleared or fixed by replacing the sensor, and a car with the work on its invoices is fine.
Air conditioning that blows cold
What to look for: Run the air conditioning on its coldest setting for a few minutes. The air from the vents should be properly cold, and it should stay cold rather than fading to ambient.
Why it matters: Air conditioning systems have failed on the A45 S, sometimes early in their lives, usually because of faulty O-ring seals near the compressor letting the refrigerant escape. Replacing the seals and regassing the system usually fixes it.
Also in the full guide
- Coolant and other warning messages
- The cold start, test drive and paperwork checks for the exact version you're viewing
The full guide to the W177 A35 or A45
The CrankSight guide walks you round the car on your phone at the viewing, with every check for the exact version you're looking at: what to look for, where to find it, and what anything you find is likely to cost. As you go it builds an assessment of that car, and if you view more than one, it lines them up side by side.
£29 for the model, used on as many cars as you like, delivered within 72 hours or your money back.
Other generations
General points for the model, last checked October 2026. Every car is different, so treat this as a guide to what to look at, not a verdict on any car. CrankSight is independent and has no connection with Mercedes-Benz.