Network, generic

U0674 Lost Communication With Wastegate Position Sensor B

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Electric wastegate actuators need position feedback so the controller can hold the turbine bypass at the commanded opening. On twin-turbo engines the second charger gets its own sensor, and U0674 says the digital frames from that sensor B have stopped or are corrupt. GM uses the sibling U0644 for wastegate A over SENT (25OBDG03B, Type A), yet none of the GM tables lists U0674. Ford's 2024 gasoline summary goes the analog way for charger B: P2ABB below 0.50 V or P2ABC above 4.50 V within 4 s, and a position error beyond 20 mm sets P25B5/P25B6. So no published source uses U0674 itself. CARB counts wastegate valve position among the diesel data items. Expect boost on that charger to be reduced or the wastegate held open.

Likely causes

Wiring to the wastegate B actuator heat-damaged or chafed
Actuator connector loose or corroded
Position sensor inside the actuator failed
Weak supply voltage or poor ground

Symptoms

  • Check engine light
  • Reduced power, boost limited on one charger
  • Sluggish response under load

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–900
Time0.5–3 h

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

Parts involved

wastegate position sensor bvehicle bus wiring

Related codes

U0644P2ABAP2ABBP2ABCP2B82P2B94

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