What it means
The closed-loop combustion controller reports that combustion performance on cylinder 11 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.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The combustion controller evaluates cylinder 11's pressure trace to estimate its contribution to engine output, using measures such as pressure development and peak pressure. This code sets when cylinder 11's calculated combustion quality falls outside the calibrated model; incorrect CAN message routing can also distort the data used in that assessment.
Common causes
Most likely first.
- Mean effective pressure outside model
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Check-engine light
- Rough running or misfire
- Reduced engine power
- Poor acceleration
How to diagnose it
- Read freeze-frame data and cylinder-specific combustion or misfire values to see when cylinder 11 fell outside its expected range.
- Check for other engine or network codes, since gateway or CAN faults can affect the pressure data used for cylinder 11.
- Inspect cylinder 11's injector, combustion-pressure sensor connections, and related wiring for damage or loose connections.
- Compare cylinder 11's live pressure-derived values with the other cylinders under the same conditions.
- If the readings remain abnormal, test cylinder 11's compression and injector operation, then check CAN message routing and network termination against the manufacturer's specification.
Common fixes
- Repair a loose or damaged connection affecting cylinder 11 pressure data.
- Correct a cylinder 11 injector fault identified by testing.
- Repair a confirmed CAN wiring or gateway routing fault.
- Replace a failed combustion-pressure sensor if testing confirms it is inaccurate.
Can I keep driving?
Avoid heavy acceleration if the engine is running roughly or has reduced power. Continued poor combustion can worsen drivability and increase emissions; stop driving if the misfire becomes severe.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.