What it means
The crankshaft position sensor B signal is outside the expected range or does not agree with other engine position data. The effect on starting or running depends on the vehicle's sensor strategy.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Crankshaft position sensor B supplies engine-position information that the controller compares with expected crankshaft timing and, where applicable, other position data. This code sets when sensor B's signal is present but its range or timing does not meet the controller's expected pattern.
Common causes
Most likely first.
- Sensor drift
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
Symptoms
- Check engine light on
- Hard starting or extended cranking
- Intermittent stalling or rough running
- Power loss
How to diagnose it
- Review freeze-frame data and live crankshaft-position readings during cranking and running to identify when sensor B's signal departs from the expected pattern.
- Inspect sensor B's mounting for looseness and check the sensor face and tone wheel for damage, debris, or an uneven gap.
- Check sensor B's connector and harness for corrosion, loose terminals, or damage that could distort the signal.
- Use a suitable scan tool or test equipment to observe sensor B's signal while cranking, and compare it with the manufacturer's specification.
- If wiring and mounting are sound, test sensor B for signal drift and check related engine-position data before replacing parts.
Common fixes
- Secure sensor B if its mounting is loose.
- Clean debris from the sensor area and correct a tone-wheel alignment or damage issue where repairable.
- Repair damaged wiring or connector terminals affecting sensor B's signal.
- Replace sensor B if its signal remains outside the specified range with correct mounting and wiring.
Can I keep driving?
The engine may start slowly, run unevenly, lose power, or stall if sensor B's position signal is unreliable. Limit driving if stalling occurs and avoid journeys where a sudden loss of power would be hazardous.
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.