P2351
Cylinder 9 Combustion Performance
What it means
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.
Is it safe to drive?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Mean effective pressure outside model
highOne of the most commonly reported causes for this code — check this first.
Injector flow has drifted
mediumA plausible cause — test and verify before replacing parts.
Gateway module routing CAN messages incorrectly
lowLess common, but worth ruling out after the more likely causes.
Related help
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