OBD-II code · Powertrain (generic, extended)
P20CA Reductant Injection Air Pressure Leakage
A leak has been detected in the air-assist branch of the DEF system — pressure decays faster than allowed when the air pump shuts off.
Is it safe to drive with P20CA?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyCracked air line or fitting
- PossibleAir pressure control valve seat leaks
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
- 0.7–3 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Air Line, Reductant Air Pressure Control Valve
Related codes
- P20C7Reductant Heater D Control Circuit Low
- P20C8Reductant Heater D Control Circuit High
- P20C9Reductant Control Module Requested MIL Illumination
- P20CBExhaust Aftertreatment Fuel Injector A Control Circuit/Open
- P20CCExhaust Aftertreatment Fuel Injector A Control Performance
- P20CDExhaust Aftertreatment Fuel Injector A Control Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.