P0406Powertrain
Powertrain · SAE
EGR Position Sensor A Circuit High
Meaning
Voltage from EGR position sensor A is above the maximum threshold, typically over 4.8 V. This indicates an open circuit in the signal wire, a short to Vref (5 V), or an internally failed sensor.
Common causes
- Open circuit in signal wire
- Short to Vref (5 V) reference voltage
- Damaged sensor with internal short to high
- Damaged connector
Symptoms
- MIL illuminated
- EGR valve stuck or commands ignored by ECU
- Possible detonation
Severity
Moderate — EGR control is compromised, resulting in increased NOx emissions.
What to do
- Check for open circuit in signal wire or short to 5 V reference
- Measure signal pin voltage (expected range 0.5–4.5 V)
- Inspect connector
- Replace sensor if wiring checks out