U0674 code meaning
Lost Communication With Wastegate Position Sensor B
Network system Generic code U06xx codes Check engine light
What U0674 means
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.
U0674 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0674
- Check engine light
- Reduced power, boost limited on one charger
- Sluggish response under load
Common causes of U0674
- Most likelyWiring to the wastegate B actuator heat-damaged or chafed
- PossibleActuator connector loose or corroded
- PossiblePosition sensor inside the actuator failed
- Less likelyWeak supply voltage or poor ground
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Wastegate position sensor bVehicle bus wiring
What each part of U0674 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 74 | The exact fault in that area. |
What to do next
- Note U0674 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0674
What does U0674 mean?
U0674 means "Lost Communication With Wastegate Position Sensor B". Electric wastegate actuators need position feedback so the controller can hold the turbine bypass at the commanded opening. It is a generic code, so it means the same on every make.
Is it safe to drive with U0674?
Drive gently and only to a workshop. With U0674 the car can go into limp mode (reduced power) to protect itself.
Will U0674 fail an emissions test?
Yes, it can. U0674 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U0674 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U0674 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.