What it means
Exhaust Aftertreatment Fuel Injector A Control Performance: the component is electrically intact but its response does not match the command. This injector doses fuel into the exhaust to raise temperature for diesel particulate-filter regeneration; it does not fuel the engine.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Exhaust aftertreatment fuel injector A doses fuel into the exhaust so heat can rise during DPF regeneration; it does not fuel the engine. P20CC sets when the injector is electrically intact but its delivery or response does not match the command, such as when a coked nozzle or low hydrocarbon supply pressure limits dosing.
Common causes
Most likely first.
- Nozzle partially coked
- HC supply pressure low
Symptoms
- Check engine light on
- Possible exhaust smoke or fuel odor during regeneration
- DPF regeneration may be impaired
How to diagnose it
- Review freeze-frame data and DPF regeneration status, then check for related injector, supply-pressure, and DPF codes.
- Inspect injector A and its connector for deposits, damage, leaks, or wiring problems that could affect its response.
- Check hydrocarbon fuel supply pressure using the manufacturer’s test procedure and compare the result with the required specification.
- Test injector A’s commanded operation and delivery according to the manufacturer’s procedure to distinguish a restricted nozzle from a supply problem.
- If injector delivery and pressure are within specification, check the control circuit and aftertreatment conditions that could prevent the expected temperature response.
Common fixes
- Restore the hydrocarbon supply if testing confirms pressure is low.
- Clean or replace injector A if its nozzle is coked and the manufacturer’s service procedure allows it.
- Repair damaged or poor electrical connections affecting injector A’s operation.
- Replace injector A if its response remains outside specification after supply and wiring faults are corrected.
Can I keep driving?
The engine may run normally, but ineffective injector A dosing can prevent proper DPF regeneration and allow soot loading to increase. Avoid repeated short trips if a regeneration warning is present, and address smoke or fuel odor during regeneration promptly.
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.