P25BARegeneration Control Switch Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P25BA concerns the dash or panel switch with which the driver starts, or on some trucks blocks, a diesel particulate filter regeneration. The engine controller reads the switch as a discrete input and sets this code when the circuit is open or otherwise unusable, so a press no longer reaches it. Volvo describes a rocker of this kind: one half inhibits automatic regeneration below 40 km/h, the other starts a parked regeneration with the truck stationary, parking brake set, gearbox in neutral and engine warm. GM's L5P trucks with option FPF instead use the exhaust brake switch for the same job (bulletin 20-NA-203). No manufacturer documents P25BA publicly. Automatic regeneration while driving continues, but a requested parked regeneration cannot be started and soot can build up.
- What you may notice
- Parked regeneration cannot be started when the cluster asks for it
- Filter or regeneration warning lamp stays on longer than usual
- Check engine lamp
- Likely causes
- LikelySwitch connector loose or unplugged behind the dash
- PossibleBroken signal or reference wire to the switch
- PossibleInternal open circuit in the regeneration switch
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.