P225ENOx Sensor Performance - Signal Biased/Stuck High (Bank 1 Sensor 2)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P225E points at the downstream NOx sensor of bank 1, behind the SCR catalyst, reading persistently high. Because that sensor sees what is left after urea dosing, a high value can be a sensor offset or genuine NOx slipping through a weak catalyst, poor DEF or a faulty dosing valve. Volvo and Mack therefore put P225E in the group where either sensor or the aftertreatment itself may be the cause: their replacement guide and bulletin KC-107 require a NOx conversion test or the aftertreatment analysis in PTT before any part is changed, and for P225E they also send technicians to the DEF dosing valve diagnosis. No public bulletin from a passenger car maker covers P225E. P225C is the same fault upstream; P225F is the low-reading downstream case.
- What you may notice
- MIL on, often together with P20EE
- Increased DEF consumption or DEF quality warnings
- Power reduction possible if SCR efficiency codes follow
- Likely causes
- LikelyReal NOx slip from a weak SCR catalyst, poor DEF quality or a faulty dosing valve
- PossibleDownstream NOx sensor with a positive offset
- RareControl software that evaluates the sensor incorrectly
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.