P0403
EGR Control Circuit
The control circuit for the EGR valve solenoid is open or shorted. The ECM cannot drive the valve to the commanded position.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
Common causes
Ordered by how often each turns out to be the cause.
- EGR solenoid winding defectiveCommon
- Wiring or connector faultPossible
- ECM driver stage damagedLess likely
Parts involved
- EGR Valve
- EGR Solenoid
- Solenoid Wiring
P0403 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.