What it means
The control module compares the vehicle speed signals from sensors A and B. It sets this code when the signals differ beyond the calibrated tolerance under monitored driving conditions.
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 signals A and B to check that both report a consistent speed. P2162 sets when the two readings differ beyond the allowed tolerance during monitored driving, which can result from a faulty sensor, damaged encoder, wiring fault, or incorrect tyre calibration.
Common causes
Most likely first.
- Faulty vehicle speed sensor A or B
- Damaged wiring or poor connection in either sensor circuit
- Damaged tone ring or encoder
- Incorrect tire size or speed calibration
Symptoms
- Check engine light on
- Speedometer may read inaccurately or fluctuate
- Transmission shifting may be erratic
- Cruise control or ABS/traction control may be affected
How to diagnose it
- Review freeze-frame data and graph vehicle speed signals A and B to see when and how their readings separate.
- Check tyre sizes and recent tyre or driveline changes that could make one speed calculation inconsistent with calibration.
- Inspect the wiring, connectors, and tone rings or encoders for both sensor A and sensor B for damage, corrosion, or debris.
- Compare each signal with scan-tool wheel-speed or other available speed data to identify which sensor is implausible.
- Test the suspect sensor and its circuit to the manufacturer's specification, then check calibration if both signals test correctly.
Common fixes
- Correct an incorrect tyre size or speed calibration.
- Clean and secure the connector for the sensor with the implausible reading.
- Repair damaged wiring in the affected A or B circuit.
- Replace the faulty sensor or repair its damaged tone ring/encoder.
- Repair a module input fault confirmed by circuit testing.
Can I keep driving?
A disagreement between signals can affect the speedometer, shifting, cruise control, or ABS/traction control. Drive cautiously and avoid relying on cruise control; get the cause checked if warning lights or erratic operation appear.
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.