Powertrain
generic / SAE
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.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number– / CA
Possible causes
- Cracked air line or fitting high
- Air pressure control valve seat leaks medium
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)
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 100–800 €
- Estimated time: 0.7–3 h
- Component: reductant air line
- Component: reductant air pressure control valve
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012