P04A4 OBD II Trouble Code Exhaust Pressure Control Valve B Stuck Open

How to easily diagnose, repair, and symptoms and causes of a P04A4 code that indicates a stuck open exhaust pressure control valve B.

Symptoms of P04A4 OBD II Trouble Code

  • Delayed engine warm up
  • Engine stall or stumble when cold
  • Diminished engine performance when cold
  • Other exhaust back pressure codes

Common Causes of P04A4 OBD II Trouble Code

  • Defective exhaust back pressure control valve position sensor
  • Bad exhaust pressure sensor
  • Faulty exhaust pressure control valve
  • Open or shorted wiring in one of the exhaust pressure control valve circuits

Severity of P04A4 OBD II Trouble Code

Since exhaust back pressure may affect climate control and drivability functions, a stored code P04A4 should be addressed with a certain degree of urgency.