The P20A2: Reductant Purge Control Valve Circuit Low refers to a fault where the circuit controlling the reductant purge valve is experiencing low voltage. The reductant purge valve is responsible for managing the flow of diesel exhaust fluid (DEF) within the emissions control system. Low voltage in the circuit can prevent proper valve operation, leading to emissions system issues. This fault may be caused by low voltage in the circuit, a faulty valve, or a malfunctioning control module.
P20A2 – Quick Overview
Code | Information |
---|---|
Meaning | P20A2: Reductant Purge Control Valve Circuit Low |
Is it serious? | Yes, it can affect the functioning of the emissions system, leading to increased emissions and potentially causing warning lights. |
Possible causes | – Low voltage in the reductant purge control valve circuit – Faulty reductant purge control valve – Faulty control module |
How to diagnose? | – Measure voltage in the control valve circuit – Test the reductant purge control valve – Check the control module functionality |
P20A2 Meaning
The P20A2 code indicates that the reductant purge control valve circuit is receiving lower voltage than expected. The valve controls the flow of DEF within the emissions system, and low voltage can cause it to malfunction, leading to improper DEF dosing. This issue may result in higher emissions and poor performance of the emissions control system. The problem could stem from faulty wiring, a bad valve, or a malfunctioning control module.
Step-by-step diagnostic guide
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check for additional fault codes related to the emissions system, which may provide more context about the issue. | OBD-II Scanner |
Measure Voltage in the Circuit | Use a multimeter to measure the voltage in the reductant purge control valve circuit and compare it to the manufacturer’s specifications to confirm low voltage. | Multimeter |
Test the Reductant Purge Control Valve | Use a diagnostic tool to test the valve and ensure it is operating correctly within the required voltage range. Replace the valve if necessary. | Multimeter, Diagnostic Tool |
Check the Control Module Functionality | Inspect the control module managing the reductant purge valve for any faults or failures in sending proper signals to the valve. | Diagnostic Tool |
Clear the Code and Test Drive | After repairs, clear the code using an OBD-II scanner and take the vehicle for a test drive to ensure the issue has been resolved. | OBD-II Scanner, Vehicle Owner’s Manual |
Recheck for Codes | Re-scan the vehicle after the test drive to ensure the P20A2 code does not return. If it reappears, further diagnostics may be needed. | OBD-II Scanner |

OBD-II scanner Buyer’s Guide
- Scanner features explained
- Different types of scanners
- Scanners for coding/odometer/ECU/checks
- Best picks + discount codes

Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)