Used-car systems
Parts & Failure Map
A practical map of known weak parts and failure patterns on used BMW, Mercedes-Benz, Audi, and Volkswagen models.
BMW
Common systems to inspect before buying.
BMW N47 Timing Chain
Rear-mounted N47 timing-chain wear is a major buyer risk because noise, service history, and repair access decide whether the car is affordable or a trap.
BMW B47 EGR Cooler
B47 EGR cooler condition matters before buying because coolant loss, recall history, and emissions faults can hide behind a normal-looking dashboard.
BMW B48 Coolant System
B48 cooling-system leaks can turn a good petrol BMW into a costly purchase if coolant residue, thermostat behavior, and service proof are ignored.
BMW ZF 8HP Gearbox
The ZF 8HP is respected, but used-car buyers still need to check fluid history, torque-converter behavior, adaptations, and engine faults that mimic gearbox issues.
BMW Turbo Actuator
BMW turbo actuator faults often appear as underboost or overboost, so buyers should verify boost control rather than replacing parts by guesswork.
BMW Valve Cover and PCV
BMW valve-cover and PCV faults can create oil leaks, crankcase pressure problems, smoke, and misfires that sellers may describe as minor seepage.
Mercedes-Benz
Common systems to inspect before buying.
Audi
Common systems to inspect before buying.
Volkswagen
Common systems to inspect before buying.
Aide à l'acheteur
Request a used-car risk review
Envoyez-nous le modèle, l'année, le moteur et le kilométrage. Nous vous aiderons à identifier les principaux risques avant d’acheter.
Il s’agit d’un guide pour l’acheteur, et non d’une inspection mécanique à distance ou d’une garantie. Vérifiez toujours la voiture en personne avec les diagnostics et les dossiers d'entretien.