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.
Low severity. Can I keep driving?You can normally keep driving. If it affects the fuel level, do not trust the gauge and refuel earlier than usual.
Symptoms
- 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
Most likely causes
- Turbocharger seal failure feeding oil into the intake
- Oil carry-over from crankcase ventilation, e.g. overfilled or diluted oil
- Combustible vapour drawn in from the surroundings
- Erroneous engine speed signal or controller fault
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- It can trigger limp mode.
- It affects emissions.
What each character of P25BD means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 5: Speed and idle
- BD: Specific fault in that system
Frequently asked questions
Can I keep driving with code P25BD?
You can normally keep driving. If it affects the fuel level, do not trust the gauge and refuel earlier than usual.
What causes code P25BD?
The most common causes are: turbocharger seal failure feeding oil into the intake; oil carry-over from crankcase ventilation, e.g. overfilled or diluted oil; combustible vapour drawn in from the surroundings.
Related codes
Sources
- gsi.ext.gm.com: 14OBDG04 Engine Diagnostics
- gsi.ext.gm.com: 18OBDG04 Engine Diagnostics
- gsi.ext.gm.com: 20OBDG04 Diagnostics
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.