P04FA
EGR A Control Temperature Too High
The ECU monitors the operating temperature of the EGR A actuator (or its control electronics). The reading has exceeded the safe upper threshold and the control unit derates or disables EGR A to protect the actuator from thermal damage.
- 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.
- Actuator overheated due to nearby exhaust heat or duty-cycle stressCommon
- Cooling jacket or air flow insufficientPossible
Parts involved
- EGR Actuator A
- EGR Cooling
P04FA 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.