What it means
The learned fuel-injector offset for cylinder 1 has reached its maximum limit. The code does not by itself establish whether the injector is under-delivering or identify the cause.
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 learns a fuel-injector offset to account for how cylinder 1 injector A delivers fuel compared with its expected response. P02CD sets when that learned offset reaches its maximum limit; the boundary reading does not alone confirm under-delivery or identify the cause.
Common causes
Most likely first.
- Injector under-delivering — clogged nozzle or worn coil
- Calibration code not programmed after replacement
Symptoms
- Check engine light on
- Misfire or rough idle on the affected cylinder
- Increased fuel consumption
- Possible fuel smell or smoke from exhaust
How to diagnose it
- Record freeze-frame data and review cylinder 1 misfire, fuel correction, and injector adaptation data to see when the maximum limit was reached.
- Check whether cylinder 1 injector A was replaced and whether its required calibration information was entered into the control module.
- Inspect the cylinder 1 injector A connector and wiring for damage, corrosion, or loose terminals that could weaken injector operation.
- Compare injector response and cylinder contribution for cylinder 1 against the other cylinders using the scan tool.
- Test cylinder 1 injector A flow and electrical control, and verify fuel pressure using the manufacturer's procedures.
Common fixes
- Enter the correct injector calibration data if it was not programmed after replacement.
- Repair damaged cylinder 1 injector A wiring or connector terminals.
- Clean or replace cylinder 1 injector A if a flow test confirms restricted delivery or a faulty coil.
- Repair a fuel-pressure or injector-driver fault if testing identifies one.
Can I keep driving?
If the engine runs smoothly and the warning light is steady, keep trips short and avoid heavy acceleration until diagnosed. Continued under-fuelling or misfire can reduce power and increase emissions; stop if the light flashes or the engine runs very roughly.
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.