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.
Medium severity. Can I keep driving?Drive without demanding power and go to a repair shop soon. If you see a lot of blue smoke or hear a metallic noise, shut off the engine.
Symptoms
- Check engine light on
- Clearly less power, boost only at base level
- Uneven boost between the turbos
- Reduced engine power message possible
Most likely causes
- Control wire of wastegate B chafed through to ground
- Valve or actuator winding B shorted
- Connector damage or moisture
- Driver stage in the engine module faulty
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It can trigger limp mode.
- It affects emissions.
What each character of P0249 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 2: Fuel injection
- 49: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0249?
Drive without demanding power and go to a repair shop soon. If you see a lot of blue smoke or hear a metallic noise, shut off the engine.
What causes code P0249?
The most common causes are: control wire of wastegate B chafed through to ground; valve or actuator winding B shorted; connector damage or moisture.
Related codes
- P0247Turbocharger/Supercharger Wastegate Actuator B
- P0250Turbocharger/Supercharger Wastegate Actuator B High
- P0248Turbocharger/Supercharger Wastegate Actuator B Range/Performance
- P0245Turbocharger/Supercharger Wastegate Actuator A Low
- P0299Turbocharger/Supercharger A Underboost Condition
Sources
- law.cornell.edu: 13 CCR 1968.2
- gsi.ext.gm.com: 18OBDG03A Engine Diagnostics
- gsi.ext.gm.com: 16OBDG05 Engine Diagnostics
- fordservicecontent.com: OBD Operations Summary Gasoline 2020 2023
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.