What Does P20A6 Mean?
The PCM has detected an open circuit or electrical fault in the reductant injection air pressure control valve circuit. This valve regulates compressed air pressure used for DEF injection and purging functions.
Common Causes
35%
Broken or disconnected wiring to air pressure control valve
30%
Failed air pressure control valve solenoid
20%
Corroded or damaged electrical connector at valve
10%
Blown fuse or relay in air pressure control circuit
5%
PCM driver circuit failure
Diagnostic Steps
1
Step 1: Visually inspect air pressure control valve connector and wiring for damage or disconnection
2
Step 2: Check all related fuses and relays for DEF/SCR air supply system
3
Step 3: Measure voltage at valve connector with key on to verify power supply
4
Step 4: Test air pressure control valve resistance and compare to specifications
5
Step 5: Verify wiring continuity between PCM and valve, check for opens or high resistance
Estimated Repair Cost
$200 - $900
Parts + labor, varies by vehicle and location
The PCM has detected an open circuit or electrical fault in the reductant injection air pressure control valve circuit. This valve regulates compressed air pressure used for DEF injection and purging functions.
The most common cause of P20A6 (Reductant Injection Air Pressure Control Valve Circuit/Open) is: Broken or disconnected wiring to air pressure control valve
Typical repair costs for P20A6 range from $200 to $900, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle remains safe to drive temporarily but may experience reduced power. Loss of air pressure control will prevent proper DEF injection and purging functions.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P20A6 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.
