The P20A4: Reductant Purge Control Valve Stuck Open fault code refers to a problem where the reductant purge control valve is stuck in the open position. This valve controls the flow of diesel exhaust fluid (DEF) within the emissions control system. A valve stuck open can result in improper DEF dosing, which may lead to increased emissions and other performance issues. The problem can be caused by a sticking valve, a faulty valve actuator, or blockages in the purge lines.
P20A4 – Quick Overview
Code | Information |
---|---|
Meaning | P20A4: Reductant Purge Control Valve Stuck Open |
Is it serious? | Yes, this can result in improper emissions control, increased emissions, and may trigger warning lights. |
Possible causes | – Sticking or jammed reductant purge control valve – Faulty valve actuator – Blocked purge lines |
How to diagnose? | – Inspect the reductant purge control valve for sticking or jamming – Test the valve actuator – Check for blockages in the purge lines |
P20A4 Meaning
The P20A4 code indicates that the reductant purge control valve is stuck open. This valve plays a crucial role in the emissions system by controlling the flow of DEF through the system. When the valve is stuck open, it can result in improper DEF dosing, leading to poor emissions control. This issue may arise from mechanical sticking of the valve, actuator problems, or blockages in the purge lines.
Step-by-step diagnostic guide
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check for additional related codes that could provide more information on the reductant system issue. | OBD-II Scanner |
Inspect the Purge Valve for Sticking or Jamming | Visually inspect the reductant purge control valve for signs of sticking or mechanical jamming that could prevent it from closing properly. | Flashlight, Safety Gloves |
Test the Valve Actuator | Use a diagnostic tool to test the functionality of the valve actuator to ensure it is operating correctly and not causing the valve to stay open. | Multimeter, Diagnostic Tool |
Check for Blockages in Purge Lines | Inspect the DEF purge lines for blockages, such as debris or crystallization, that may prevent proper operation of the valve. | Flashlight, Inspection Mirror |
Clear the Code and Test Drive | After completing repairs, clear the fault code using an OBD-II scanner and take the vehicle for a test drive to verify that the issue has been resolved. | OBD-II Scanner, Vehicle Owner’s Manual |
Recheck for Codes | After the test drive, re-scan the vehicle to ensure the P20A4 code does not return. If it reappears, further diagnostics may be needed. | OBD-II Scanner |

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