P2351
Cylinder 9 Combustion Performance
The closed-loop combustion controller reports that combustion performance on cylinder 9 is below the calibrated quality metric. Computed from the cylinder pressure trace — IMEP (indicated mean effective pressure), CA50 (50% mass burnt angle) or peak pressure deviates from the model.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Common causes
Ordered by how often each turns out to be the cause.
- Mean effective pressure outside modelCommon
- Injector flow has driftedPossible
- Gateway module routing CAN messages incorrectlyLess likely
Parts involved
- Cylinder 9 Combustion
- Cylinder Pressure Sensor 9
- Fuel Injector Cyl 9
P2351 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.