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P20A5 Powertrain

Reductant Purge Control Valve A Stuck Closed

Reductant purge control valve A is mechanically stuck closed — DEF lines cannot be vented at shutdown, increasing risk of freeze damage in winter.

Affected components

  • Reductant purge valve

Common causes

  • High likelihood: Valve stuck closed mechanically
  • Low likelihood: Carbon or debris buildup preventing free movement
  • Low likelihood: Component wear with age - mechanical play

Possible symptoms

  • Check engine light or NOx warning on
  • AdBlue/DEF level or quality warning
  • Possible no-start countdown after ignore period
  • Failed emissions inspection (NOx)

Diagnostic notes

  • The malfunction indicator lamp may illuminate
  • This code can affect emissions

Related codes

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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