BMW · Audi · Mercedes-Benz

Everything for your German car, in one place

Fault diagrams, OBD2 code reading, build planning and verified parts fitment for BMW, Audi and Mercedes-Benz models from the 1990s to today.

Try “P0171 on an N54” or a full 17-digit VIN.

Browse models1990 → today Parts & toolsFitment checked OBD2 scannerRead live data Car valuePhoto appraisal

German autobahn at night with amber and white light trails on wet asphalt

Coverage right now

Generations

Engines

Body styles

Every generation gets a systems diagram, failure-point charts and a fitment-checked parts list.

Browse by chassis

Pick your platform

All models

BMW generations by decade

1990s

2000s

2010s

2020s

Owner toolkit

Work through it step by step

Ranked causes, real test steps, parts, tools, cost and difficulty — written like a master tech writes a work order, with “verify this” instead of an invented torque spec.

Fault diagnosisAnswer a few targeted questions and get a ranked cause list with the test that confirms each one.Try it →Build plannerVehicle, budget, power goal in — a staged parts list with supporting mods and costs out.Try it →Parts compatibilityFitment answers with the adapters, offsets and coding the swap actually needs.Try it →Maintenance plannerMileage-aware service checklist plus the known failure points for your engine.Try it →

OBD2 ScannerRead and clear fault codes with an ELM327 adapter, watch live sensor data, or decode any P-code and BMW hex code.Scan my car →

Trending this week

Repairs & guides

N54

Walnut blasting intake valves

DIY · 4h · Difficulty 3/5

N52

Starter replacement without dropping the intake

DIY · 3h · Difficulty 4/5

N55

Charge pipe failure and boost leak testing

Repair · 1.5h · Difficulty 2/5

S65

Rod bearing service interval reality check

Guide · 8h · Difficulty 5/5

E9x

P0012 VANOS: solenoid, oil or timing?

Diagnosis · 2h · Difficulty 3/5

B58

Stage 1 vs Stage 2: what actually changes

Tuning · Read · 8 min

Stuck on something right now?

Describe the symptom, the chassis and the engine. You'll get a diagnosis path in seconds.

Start a diagnosis