The most common DTCs are P0403, P0404 and P0405. Below are the definitions, and if you haven't modified your vehicle, then the EGR valve is the most likely cause.
- P0403: EGR Exhaust gas recirculation control circuit: open circuit, short to ground, short to voltage, faulty valve, faulty PCM.
- P0404: EGR Exhaust gas recirculation control circuit range/performance: difference between command and actual exceeds a specified limit.
- P0405: EGR Exhaust gas recirculation sensor: a circuit low voltage below a specified range.