Mercedes-Benz A 45 AMG
World record holder at launch: the M133 was the world's most powerful production four-cylinder in 2013. 2.0 litres, 360 hp, 1.8 bar boost — absurd on paper, surprisingly reliable in practice. The well-known weakness is oil contamination of the turbo oil supply line on early vehicles (before Feb. 2014), which led to a recall. The 7G-DCT dual-clutch overheats under hard use in stop-and-go traffic. Keep to service intervals and treat the gearbox gently and you get a long-lived high-performance engine.
A 45 AMG — Even Sharper
280 kW after the facelift, with a sharper chassis and more thrust — the W176 AMG 45 is and remains an icon of compact performance.
Engine Weaknesses 9
Recall campaign for vehicles built before Feb. 2014: contaminated oil feed line to the turbo causes bearing wear and turbo damage. 365 affected vehicles.
Symptoms: Power loss, oil mist from exhaust, whistling from turbocharger, in extreme cases engine failure
The 7G-DCT dual-clutch gearbox frequently shows judder when pulling away on the M133 AMG. The clutch wears prematurely due to high torque spikes. Repair costs €3,500–€6,000.
Symptoms: Judder when pulling away and during gear changes (especially cold), slipping clutch feel, gearbox enters limp mode
The M133 AMG shares the well-known Mercedes issue of leaking camshaft solenoids. Accelerated by higher engine temperatures in the AMG application.
Symptoms: Lambda sensor faults, rough idle, CEL. As it progresses, multiple electrical codes. Oil traces at camshaft solenoids
Recall for 365 vehicles built before Feb. 2014: residual contamination of the oil feed line could cause power loss or turbocharger damage. Only affects early production A45 and CLA45.
Under extreme use the turbocharger impeller can develop shaft play. In the worst case the wheel can detach and introduce foreign objects into the combustion chamber, causing engine damage.
Symptoms: Whistling or hissing noise, power loss, in extreme cases engine damage
The highly-tuned M133 tends towards elevated oil consumption through worn valve stem seals and PCV system, especially with spirited driving.
Symptoms: Dropping oil level between oil changes, occasional blue smoke on cold start or overrun
The M133 timing chain can stretch prematurely with regular high-rpm use and generate rattling noises. Critical when oil change intervals are exceeded.
Symptoms: Rattling on cold start, rough idle, sporadic hesitation under load
The high-pressure fuel pump of the M133 is marginally designed for 360–381 hp. Fault codes for too-high or too-low fuel pressure occur. Pump replacement €1,500–€4,000.
Symptoms: CEL, fuel pressure fault codes P0087/P1223, hesitant throttle response, misfires under load, occasional limp mode
The AMG Speedshift 7G-DCT overheats in frequent stop-and-go on motorway construction sites. Gearbox goes into limp mode. Mercedes acknowledged this as a design characteristic. Software update can reduce frequency.
Symptoms: Gearbox enters limp mode, jerky gear changes, warning message in instrument cluster
Vehicle Weaknesses 7
Recall due to defective windscreen bonding. In an accident the screen may detach and occupant protection cannot be guaranteed. Affects vehicles up to July 2013.
7G-DCT judders when pulling away and during shifts 1–3, especially during the cold warm-up phase. Software updates often help but do not always solve the problem permanently. Clutch wear increased in urban traffic.
Xenon headlights of early model years permanently mist up internally. A complete xenon headlight costs over €1,000. LED headlights of facelift models (from autumn 2015) significantly more robust.
Certain condenser batch has defective welds and loses refrigerant. Replacement costs €1,200 including labour. Recall for A/C as fire risk known.
Early infotainment system (COMAND) of pre-facelift version freezes, starts slowly or crashes. Collision warning PRE-SAFE triggers false emergency braking. Software updates required.
According to MOT reports, indicators and hazard warning lights fail more than average on the W176. Defective relays or control units are usually the cause.
Plastic trim panels in the interior, panoramic roof and boot cover produce annoying creaking and rattling noises. Cheap interior for the brand's level is a common criticism.