What it means
The control module has detected a fault in vehicle speed sensor B or its circuit. The location and function of sensor B depend on the vehicle.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Vehicle speed sensor B supplies a speed signal to the control module, though its location and role vary by vehicle. This code indicates a fault in sensor B or its circuit; it does not by itself specify whether the signal is low, high, or out of range.
Common causes
Most likely first.
- Sensor failed
- Harness fault
Symptoms
- Speedometer may read incorrectly or fluctuate
- Transmission shifting may be harsh or delayed
- Cruise control may not work
- ABS or traction-control warning light may come on
How to diagnose it
- Record freeze-frame data and scan for related ABS, transmission, or speed-sensor codes to identify when the sensor B fault occurs and which systems share the signal.
- Compare live vehicle-speed data from sensor B with other available wheel or vehicle speed readings during a safe, steady-speed drive.
- Inspect sensor B, its connector, and the harness along its route for damage, contamination, corrosion, or loose connections.
- Check the sensor B supply, ground, and signal circuit as applicable to the vehicle, comparing readings with the manufacturer's specification.
- If the wiring and connections pass, test sensor B itself and check its mounting or target according to the vehicle's service information.
Common fixes
- Repair damaged or poorly connected sensor B wiring.
- Clean corrosion or contamination from the sensor B connector and secure it.
- Correct sensor B mounting or target damage if the vehicle's service information identifies a problem.
- Replace vehicle speed sensor B if its circuit and installation check out but its signal remains faulty.
Can I keep driving?
Drive cautiously until the fault is diagnosed: an inaccurate speed signal can affect the speedometer, cruise control, transmission shifting, or stability systems. Avoid relying on cruise control and allow extra distance if ABS or traction-control warnings are also on.
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.