What it means
The closed-loop combustion controller reports that combustion performance on cylinder 7 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 7 using its pressure trace and measures such as indicated pressure and combustion timing. This code means cylinder 7's calculated combustion performance falls outside the controller's acceptable range; injector flow drift or faulty communication can contribute.
Common causes
Most likely first.
- Injector flow rate drift
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Check-engine light
- Rough or uneven engine running
- Misfire or hesitation
- Reduced engine power
How to diagnose it
- Record freeze-frame data and available cylinder 7 pressure, combustion timing, and misfire values to see which operating conditions trigger the fault.
- Compare cylinder 7's combustion data with the other cylinders for an isolated performance difference.
- Inspect the cylinder 7 injector connector and harness, then check available injector operation or flow data for a cylinder-specific deviation.
- Verify that live cylinder 7 pressure data responds plausibly and inspect the sensor wiring and connections.
- If the cylinder and sensor checks are sound, review combustion-controller communication and gateway fault data using the manufacturer's diagnostic information.
Common fixes
- Repair a poor cylinder 7 injector connection or damaged wiring.
- Service or replace a cylinder 7 injector if testing confirms flow drift.
- Repair a confirmed cylinder 7 pressure sensor or circuit fault.
- Correct a verified gateway or combustion-controller communication fault using the manufacturer's procedure.
Can I keep driving?
If the engine runs smoothly, limit driving and arrange diagnosis soon. Avoid heavy loads if it hesitates or loses power, since poor combustion can increase emissions and lead to misfire-related damage.
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.