P25BDUnmetered Fuel - Forced Engine Shutdown
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P25BD protects against engine runaway, where the engine keeps speeding up although the controller injects no fuel, for instance because oil from a failed turbocharger seal or combustible vapour drawn into the intake is being burned. GM documents the monitor in its diesel ECM tables. In 14OBDG04 the speed must pass 5,400 rpm for 0.01 s, after which the controller cuts the air supply with its intake air valve and disables the injectors; 18OBDG04 uses 5,500 rpm for 0.5 s and 20OBDG04 5,200 rpm for 0.1 s, both enabled above 1,500 rpm. Each table rates it Type A, so the MIL comes on in the first trip. Unlike P0219, which merely records an overspeed, P25BD means the engine was forcibly stopped. Before a restart, turbo, crankcase ventilation and intake tract should be checked for oil.
- What you may notice
- Engine revs up uncontrollably and then shuts off
- Heavy smoke from the exhaust before shutdown
- Check engine lamp on immediately
- Possible severe engine damage after the event
- Likely causes
- LikelyTurbocharger seal failure feeding oil into the intake
- PossibleOil carry-over from crankcase ventilation, e.g. overfilled or diluted oil
- RareCombustible vapour drawn in from the surroundings
- RareErroneous engine speed signal or controller fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €300 – €8,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.