P0407Powertrain
Powertrain · SAE
EGR Position Sensor B Circuit Low
Meaning
Signal voltage on EGR position sensor channel B is below the minimum threshold. This code applies to circuit B of a dual-track EGR position sensor, common on electronic EGR valves with redundant position feedback.
Common causes
- Short to ground on channel B signal wire
- Connector fault on channel B
- Dual-track sensor failure
Symptoms
- MIL illuminated
- EGR position feedback degraded
- Possible detonation
Severity
Moderate — EGR control is compromised, resulting in increased NOx emissions.
What to do
- Measure voltage at channel B signal pin (expected range 0.5–4.5 V)
- Check channel B circuit for short to ground
- Inspect connector and sensor body
- Replace sensor if channel B wiring is intact