What it means
The reported vehicle speed does not correlate with transmission output shaft speed within the expected range.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The control module compares vehicle speed reported by the vehicle speed sensor with transmission output shaft speed, which reflects how quickly the transmission output is turning. P215B sets when the relationship between those readings falls outside the expected range, potentially because a sensor signal, tyre calibration, or driveline behavior is wrong.
Common causes
Most likely first.
- Faulty vehicle speed sensor or output shaft speed sensor
- Damaged wiring or connectors in either sensor circuit
- Incorrect tire size or speed calibration
- Transmission or driveline fault affecting speed readings
Symptoms
- Check engine light on
- Speedometer may read inaccurately
- Transmission shifting may be harsh or erratic
- Cruise control may not work
How to diagnose it
- Review freeze-frame data and scan-tool live readings for vehicle speed and output shaft speed, noting when their relationship becomes implausible.
- Check tyre sizes and any recent changes to tyres, final drive, or speed calibration that could alter the expected relationship.
- Inspect both sensor connectors and harnesses for loose pins, corrosion, fluid intrusion, or damage.
- Graph both speed signals during a cautious road test to identify which reading drops out, spikes, or diverges.
- Test the vehicle speed and output shaft speed sensors and circuits to the manufacturer's specification, then investigate transmission or driveline faults if signals pass.
Common fixes
- Secure or clean a loose or corroded sensor connector.
- Repair damaged wiring in the affected vehicle-speed or output-speed circuit.
- Replace the sensor shown by testing to have an incorrect or missing signal.
- Restore the specified tyre size or correct the speed calibration.
- Repair the transmission or driveline fault causing an implausible output speed.
Can I keep driving?
A short cautious trip may be possible if shifting and speed indication remain normal, but erratic shifting or a fluctuating speedometer can make driving unpredictable. Avoid towing or hard acceleration if the transmission is shifting harshly, and arrange diagnosis soon.
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.