Engine and gearbox (P)
P0720: Output speed sensor circuit fault
The transmission output speed sensor is not sending a correct signal. This can affect the transmission's ability to shift gears properly.
Checked by a licensed car technician · last reviewed 29 September 2026
Symptoms
- Check engine light is on
- Transmission may not shift correctly
- Speedometer may not work
- Reduced fuel efficiency
Common causes
- Faulty output speed sensor
- Damaged internal wiring harness
- Contaminated or corroded connector
- Faulty transmission control module
How to check it yourself
- Inspect the output speed sensor for damage
- Check the wiring and connectors for corrosion or damage
- Test the sensor with a multimeter
- Compare input and output speeds using diagnostic tools
Can I keep driving?
The car can be driven, but avoid harsh acceleration and high speeds until the issue is resolved.
General guidance, not a professional inspection. Confirm faults with measurements before buying parts, and use a qualified mechanic for brakes, steering, fuel leaks, airbags, and other safety-critical work. Terms and disclaimer