Exhaust Gas Recirculation Sensor "B" Circuit
The EGR (Exhaust Gas Recirculation) Sensor B circuit has a malfunction detected by the engine control module. This sensor monitors the position of the EGR valve pintle to ensure proper exhaust gas recirculation flow, which is critical for emissions control and engine performance.
What You Might Notice
- Service Engine Soon light illuminated
- Rough idle or engine stalling
- Hesitation during acceleration
- Reduced fuel economy
- Additional EGR-related fault codes (P0405 or P0406) may appear
Most Common Causes
- 1
EGR Sensor B failure
The EGR sensor itself has failed electrically or mechanically, preventing accurate position readings to the engine control module.
- 2
Wiring harness or connector issues
Corroded, damaged, or loose connections in the EGR sensor circuit prevent proper signal transmission to the PCM.
- 3
EGR valve carbon buildup
Excessive carbon deposits cause the EGR valve pintle to stick, preventing the sensor from detecting proper valve movement and position.
- 4
Engine control module (PCM) malfunction
A faulty PCM may misinterpret valid sensor signals or have corrupted programming related to EGR sensor monitoring.
How to Diagnose It
- 1
Check EGR Sensor B failure — The EGR sensor itself has failed electrically or mechanically, preventing accurate position readings to the engine control module.
- 2
Check Wiring harness or connector issues — Corroded, damaged, or loose connections in the EGR sensor circuit prevent proper signal transmission to the PCM.
- 3
Check EGR valve carbon buildup — Excessive carbon deposits cause the EGR valve pintle to stick, preventing the sensor from detecting proper valve movement and position.
- 4
Check Engine control module (PCM) malfunction — A faulty PCM may misinterpret valid sensor signals or have corrupted programming related to EGR sensor monitoring.
How to Fix It
- 1
Inspect and clean EGR valve and sensor
Remove the EGR valve assembly and clean carbon deposits from the valve pintle and seat. Inspect the EGR sensor for proper operation and clean electrical contacts. Reinstall and test.
- 2
Replace EGR Sensor B
If the sensor is confirmed faulty through testing, remove the old sensor and install a new OEM or quality aftermarket replacement, ensuring proper electrical connector seating.
- 3
Repair wiring harness and connectors
Inspect the EGR sensor circuit wiring for corrosion, breaks, or loose connections. Repair or replace damaged wiring and clean corroded connectors with electrical contact cleaner.
- 4
Replace engine control module (PCM)
If wiring, connections, and sensor are confirmed good but code persists, the PCM may be faulty and require replacement. This is a last-resort fix and should be done by a qualified technician.
Need a deeper diagnosis?
Search for related repair guides or browse by system.