P0249Turbocharger/Supercharger Wastegate Actuator B Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- The wastegate lets exhaust bypass the turbine to limit boost; actuator B is either a pulse-width-modulated solenoid on a pneumatic wastegate can or an electric actuator with a position sensor. B is the second turbo or actuator, so B codes only exist on engines with two. P0249 means the control circuit of actuator B reads low, typically the control wire shorted to ground. On GM's LGW twin-turbo less than 0.5 Ω to ground with the driver off in 10 of 20 samples sets it with the warning light in the first trip; older GM modules need two trips. Ford reports it on pneumatic wastegates after 2–3 s. Boost control is then switched off and only the spring-set base boost remains – less power, but no risk of overboost.
- What you may notice
- Check engine light on
- Clearly less power, boost only at base level
- Uneven boost between the turbos
- Reduced engine power message possible
- Likely causes
- LikelyControl wire of wastegate B chafed through to ground
- PossibleValve or actuator winding B shorted
- PossibleConnector damage or moisture
- RareDriver stage in the engine module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €30 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.