P046FEGR Sensor B Circuit Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. Which part EGR sensors A and B are depends on the maker: sensor A is usually the position sensor of EGR valve A; GM's Duramax diesels of 2017/18 use sensor B for the coolant temperature sensor at the inlet of the high-pressure EGR cooler, FCA for the position sensor of the low-pressure valve. P046F means jumps or dropouts of sensor B. GM's Duramax diesels set it when the value leaves a narrowing window around the last valid reading – 40 of 50 samples of 100 ms, MIL after two trips. A substitute value is then used and EGR cooler monitoring is suspended. Usually a loose contact or broken wire is the cause.
- What you may notice
- Check engine light on, may come and go
- Usually no change in driving
- Likely causes
- LikelyLoose contact at the sensor connector
- PossibleChafed wire or vibration break
- PossibleSensor faulty internally
- RareEngine module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €30 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.