What it means
The measured fuel injection quantity for group C is below the calibrated window. Injector flow drift, rail pressure off, or measurement bias.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The engine control module estimates fuel delivery for injection group C from injector operation and fuel-system data. It compares that quantity with the calibrated range. This code sets when group C delivers less fuel than expected, which can cause lean running or misfire.
Common causes
Most likely first.
- Injectors partially clogged
- Fuel rail pressure low
Symptoms
- Check-engine light
- Rough running or misfire
- Reduced power or acceleration
- Hard starting
How to diagnose it
- Record freeze-frame data and check live misfire counts and fuel-quantity data to see when group C falls below its expected range.
- Inspect the group C injector connectors and harness for loose pins, corrosion, chafing, or damage that could reduce injector operation.
- Check for fuel leaks and review available fuel-pressure data under the conditions shown in the freeze frame.
- Test fuel rail pressure against the manufacturer's specification, since low pressure can reduce delivery across group C.
- If pressure and wiring are sound, evaluate group C injectors for restricted flow using the manufacturer's specified balance or flow test.
Common fixes
- Repair loose, corroded, or damaged group C injector wiring and connections.
- Correct a fuel supply or pressure fault if rail pressure is below the manufacturer's specification.
- Clean or replace a partially clogged group C injector as indicated by testing.
- Recheck fuel-quantity and misfire data after repairs to confirm group C delivery is within range.
Can I keep driving?
Limit driving if the engine runs roughly, misfires, or lacks power; continued misfire can damage the catalytic converter and poor fueling can worsen drivability. If it is difficult to start or stalls, avoid driving until the cause is addressed.
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.