P25BD
Unmetered Fuel - Forced Engine Shutdown
The engine controller commanded a forced shutdown after detecting unmetered fuel reaching the combustion chambers. Common on diesels with leaking turbo seals or cracked intercoolers that drip oil into the intake — the engine then runs on the oil and can overspeed.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
Common causes
Ordered by how often each turns out to be the cause.
- Turbocharger oil seal leak feeds engine oil into the intakeCommon
- Oil collected in the intercooler is sucked into the engine on loadPossible
- Failed PCV / crankcase breather floods intake with oil mistPossible
Parts involved
- Turbocharger Seals
- Intercooler
- Intake Manifold
- Air Shutoff Valve
P25BD is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.