What it means
Position sensor B signal voltage above the upper limit — short to reference voltage or open signal return.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Turbo boost control uses an actuator to position a wastegate or variable vanes, and sensor B reports that position to the engine control module. This code sets when sensor B's signal rises above the circuit's expected upper limit, which can result from a short to the reference supply or an open signal return path. The module may restrict boost because it cannot rely on sensor B's feedback.
Common causes
Most likely first.
- Signal wire shorted to reference voltage
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check-engine light on
- Reduced engine power or turbo boost
- Limp mode may occur
How to diagnose it
- Record freeze-frame data and compare live readings from position sensors A and B to confirm whether sensor B is stuck high or reporting an implausible value.
- Locate sensor B using the vehicle's wiring information and inspect its connector and harness for pinched wires, corrosion, loose pins, or contact with a power source.
- Check the signal wire for a short to the reference supply and inspect the signal return and ground connections using the manufacturer's wiring diagram.
- Monitor sensor B while gently moving the harness to identify a short or open connection that changes with movement.
- If the wiring and connections are sound, test sensor B and its reference and return circuits using the manufacturer's procedure.
Common fixes
- Repair a signal wire shorted to the reference supply.
- Repair a pinched or damaged wire contacting a power source.
- Clean or repair corroded or loose sensor B connector contacts.
- Replace a confirmed faulty sensor B or actuator assembly if the sensor is not separately serviceable.
Can I keep driving?
Avoid hard acceleration, towing, and high-load driving if boost or engine power is limited. Do not rely on normal turbo response until sensor B's circuit is repaired, since the control module may restrict boost.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.