29E0
High29E0 — Fuel Mixture Regulation, Bank 1
Description
What the Code Means
29E0 is set by the DME when the air-fuel mixture on bank 1 deviates from the calculated value. The code wording is ambiguous: it can mean either a lean or a rich mixture, so the direction of the deviation has to be confirmed with diagnostics — in the case we tore down, EDIABAS showed a lean mixture while the OBD code pointed to rich.
In the original case the engine was idling and the DME cut fuel delivery by 46.1% to compensate — a negative correction that large points to leaking injectors that keep delivering fuel with the valves closed.
Symptoms
Symptoms
- Rough idle;
- illuminated Check Engine light;
- fuel trim beyond 20%;
- possible misfires.
Causes and fixes
Diagnosis and Repair
- Read the codes with ISTA or INPA to determine the direction of the deviation — lean or rich.
- Check the fuel trims (LTFT, integrator) and assess their magnitude.
- Run an injector leak test — pull them and pressurize to check for seepage.
- Replace the leaking injectors with genuine BMW units (for the N53).
- Clear the adaptations and do a verification check.
Possible secondary damage
Secondary Damage
- Leaking injectors dilute the engine oil with fuel, which leads to bearing wear;
- unburned fuel damages the catalytic converter and oxygen sensors;
- continued driving can cause hydrolock and engine damage.