Exhaust Aftertreatment Fuel Air Purge Valve Stuck Open
On systems that inject HC dosing fuel or AIR-assisted reductant into the aftertreatment, a purge valve clears the line after each dosing event. The ECM detects the valve stuck open — pressure or flow does not build up against a closed valve, so the dosing line cannot be charged. Common on diesel HC-doser hardware (DPF regen support).
Affected components
- Aftertreatment purge valve
- Dosing line
Common causes
- High likelihood: Mechanically stuck open valve from soot or coking
- Medium likelihood: Broken return spring
- Low likelihood: Carbon or debris buildup preventing free movement
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.