OBD-II code · Powertrain (generic, extended)
P20A6 Reductant Injection Air Pressure Control Valve Circuit/Open
The drive circuit for the air-assist pressure-control valve in the DEF system is open — atomisation pressure cannot be regulated, dosing accuracy degrades.
Is it safe to drive with P20A6?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySolenoid winding open
- Less likelyPin pushed back out of connector body
- Less likelyCracked solder joint inside the module or sensor
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.7–2.5 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Air Pressure Control Valve
Related codes
- P20A3Reductant Purge Control Valve A Circuit High
- P20A4Reductant Purge Control Valve A Stuck Open
- P20A5Reductant Purge Control Valve A Stuck Closed
- P20A7Reductant Injection Air Pressure Control Valve Performance
- P20A8Reductant Injection Air Pressure Control Valve Circuit Low
- P20A9Reductant Injection Air Pressure Control Valve Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.