BMW OBD Codes
decoded & explained
The codes BMW owners actually see — misfires, lean mixtures, O2 sensors and EVAP — with clear causes and fixes. Plus a free decoder.
BMW check engine light codes
BMW uses the standard OBD-II system on petrol and diesel models, so a generic scanner reads most engine codes. In parallel, BMW’s own modules (DME, DDE) also store hexadecimal codes that only dealer-level tools (ISTA/INPA) can read.
The codes below are the P-codes most frequently reported by BMW and MINI owners — the ones that trigger the check engine light.
OBD-II code decoder
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Most common BMW
The most common BMW faults behind these codes.
| Code | Description |
|---|---|
| P0171 | System Too Lean (Bank 1) |
| P0174 | System Too Lean (Bank 2) |
| P0300 | Random/Multiple Cylinder Misfire |
| P0335 | Crankshaft Position Sensor Circuit |
| P0420 | Catalyst System Efficiency Below Threshold (Bank 1) |
| P0442 | EVAP System Small Leak Detected |
| P12A5 | Faulty DME/ECU Communication |
| P2A00 | O2 Sensor Circuit Range/Performance (Bank 1, Sensor 1) |
Common BMW faults
The most common BMW faults behind these codes.
Cylinder misfires (P0300 series) — usually ignition coils, spark plugs, or VANOS/VALVETRONIC issues.
Lean mixture (P0171/P0174) — vacuum leaks in the intake, crankcase breather, or MAF sensor.
Catalyst efficiency (P0420) — aging catalytic converter or upstream O2 sensor.
EVAP small leak (P0442) — fuel cap, purge valve or a cracked line.
O2 sensor aging (P2A00) — slow switching, common around 100,000 km.
BMW FAQ
Why does my BMW misfire at idle?
Can I read BMW codes with a cheap scanner?
Is P0420 expensive to fix on a BMW?
What causes the P0171 lean code?
Does BMW warranty cover engine codes?
Codes vary slightly by model, year and engine. Always confirm with a proper diagnosis. Manufacturer-specific codes (P1xxx/P2xxx) may differ from generic descriptions.
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Decode your BMW code now
Use the free decoder below, or browse the most common BMW codes.