What Does P20A3 Mean?
The PCM has detected an abnormally high voltage condition in the reductant purge control valve circuit. This typically indicates an open circuit, loss of ground, or valve driver issue preventing normal operation.
Common Causes
35%
Open circuit in valve control wire or ground wire
25%
Poor ground connection at valve or chassis ground point
20%
Failed purge valve with open internal windings
15%
Corroded connector terminals causing high resistance
5%
PCM driver circuit failure maintaining high voltage
Diagnostic Steps
1
Step 1: Check and clean all ground connections for purge valve circuit
2
Step 2: Measure voltage at valve connector with key on (should see battery voltage on power, ground on control)
3
Step 3: Backprobe valve connector and command operation to verify PCM is switching circuit
4
Step 4: Test continuity in all wires between PCM and valve connector
5
Step 5: Measure purge valve resistance and compare to specifications for open coil
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
The PCM has detected an abnormally high voltage condition in the reductant purge control valve circuit. This typically indicates an open circuit, loss of ground, or valve driver issue preventing normal operation.
The most common cause of P20A3 (Reductant Purge Control Valve Circuit High) is: Open circuit in valve control wire or ground wire
Typical repair costs for P20A3 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive temporarily but vehicle may enter limp mode. Failure to repair will result in DEF system malfunction and potential crystallization damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P20A3 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control System (SCR/DEF)
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
