P0490Powertrain
Powertrain · SAE
EGR Control Circuit A High
Meaning
The ECU detects above-expected voltage on EGR actuator control output A, indicating an open circuit or a short to supply voltage. The EGR valve cannot be controlled.
Common causes
- Open circuit in EGR actuator wiring (broken wire or damaged connector)
- Short to battery voltage on the control wire
- Failed EGR actuator with open winding (infinite resistance)
Symptoms
- MIL illuminated
- EGR valve non-functional
- Increased emissions and possible detonation
Severity
Moderate severity: consequences are equivalent to P0489 — a non-functional EGR increases emissions and may cause detonation.
What to do
- Measure EGR solenoid winding resistance (open circuit indicates a failed solenoid)
- Check for short to battery voltage on the signal wire
- Inspect connector and harness for breaks
- Repair harness or replace actuator