P20A4 OBD II Trouble Code Reductant Purge Control Valve Stuck Open

How to quickly diagnose and repair, and causes of a P20A4 code which indicates a detected stuck open reductant purge control valve.

Symptoms of P20A4 OBD II Trouble Code

  • Poor engine performance
  • Decreased fuel economy
  • Check engine light illuminated

Common Causes of P20A4 OBD II Trouble Code

  • Defective reductant purge control valve
  • Faulty or damaged wiring
  • Loose or defective control module ground strap
  • Corroded, damaged or loose connector
  • Defective fuse or fuse-able link (If applicable)
  • Defective PCM or ECM

Severity of P20A4 OBD II Trouble Code

The severity of this code is normally moderate, but P20A4 can be severe if harmful gases are being expelled from the exhaust which becomes a safety concern requiring immediate attention.