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P20A6 Powertrain

Reductant Injection Air Pressure Control Valve Circuit/Open

The drive circuit for the air-assist pressure-control valve in the DEF system is open — atomisation pressure cannot be regulated, dosing accuracy degrades.

Affected components

  • Reductant air pressure control valve

Common causes

  • High likelihood: Solenoid winding open
  • Low likelihood: Pin pushed back out of connector body
  • Low likelihood: Cracked solder joint inside the module or sensor

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

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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