OBD-II code · Powertrain (generic, extended)
P2038 Reductant Injection Air Pressure Sensor A Circuit Range/Performance
The reductant injection air-pressure sensor A reads inside the electrical range but does not match expected behaviour over time or load — slow response or wrong offset.
Is it safe to drive with P2038?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySensor drift
- Less likelySensor element aged beyond calibration window
- Less likelySensor mounting loose - signal damping
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 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Air Pressure Sensor
Related codes
- P2037Reductant Injection Air Pressure Sensor A Circuit
- P209BReductant Injection Air Pressure Sensor B Circuit Range/Performance
- P2035Exhaust Gas Temperature Sensor Circuit Low (Bank 2 Sensor 2)
- P2036Exhaust Gas Temperature Sensor Circuit High (Bank 2 Sensor 2)
- P2039Reductant Injection Air Pressure Sensor A Circuit Low
- P203AReductant Level Sensor A Circuit
- P203BReductant Level Sensor A Circuit Range/Performance
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.