P0403Powertrain
Powertrain · SAE
EGR Control Circuit Malfunction
Meaning
The ECU detects an open circuit, short to ground, or short to voltage in the EGR solenoid or actuator motor control wiring. The EGR cannot be commanded.
Common causes
- Open circuit in EGR solenoid wiring harness
- Short to ground or battery voltage on control wire
- Failed EGR solenoid coil (open or shorted winding)
- ECU output driver fault
Symptoms
- MIL illuminated
- EGR permanently non-functional
- Possible detonation at cruise
- High NOx emissions
Severity
Moderate — a disabled EGR system raises combustion temperature and NOx emissions.
What to do
- Measure EGR solenoid resistance and compare to specification
- Check control wiring for shorts or open circuits
- Verify ECU output voltage when commanding EGR
- Repair wiring or replace solenoid as needed