P040B OBD II Trouble Code Exhaust Gas Recirculation Temperature Sensor A Circuit Range/Performance

How to quickly diagnose, repair, and what causes a P040B code that indicates a range or performance problem within the A EGR temperature sensor circuit.

Symptoms of P040B OBD II Trouble Code

  • Failed smog or emissions state/provincial test
  • Engine noise (knocking, rattling, pinging, etc.)
  • Louder exhaust
  • Excessive exhaust smells

Common Causes of P040B OBD II Trouble Code

  • Defective or damaged EGR (Exhaust Gas Recirculation) temperature sensor
  • EGR temperature sensor gasket leaking
  • Cracked or leaking exhaust pipe in which the sensor is mounted
  • Burnt wiring harness and/or sensor
  • Damaged wire(s) (open, short to power, short to ground, etc.)
  • Damaged connector
  • ECM (Engine Control Module) issue
  • Poor connections

Severity of P040B OBD II Trouble Code

Severity here varies significantly depends on your particular issue but I wouldn't classify this as severe given the fact that the entire system was introduced to vehicles simply as an emission reduction strategy. That being said exhaust leaks aren't "good" for your vehicle nor are leaking or defective EGR temp sensors so maintenance is the key here, sooner rather then later!