Powertrain, generic · Fuel and air metering (injector circuit)

P0249 Turbocharger/Supercharger Wastegate Actuator B Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

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

Symptoms

  • Check engine light on
  • Clearly less power, boost only at base level
  • Uneven boost between the turbos
  • Reduced engine power message possible

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–400
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

wastegate actuator bwastegate solenoid valveactuator wiring

Related codes

P0247P0250P0248P0245P0299

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com.