P0720 — Output Speed Sensor Circuit Malfunction
serious
What it means
The signal from the output shaft speed sensor, which reports how fast the gearbox output shaft turns, is missing, noisy or implausible compared with the wheel speed data. The transmission module uses this value together with input speed to verify gear ratio and to time shifts, and on many cars it also feeds the speedometer. Symptoms include a dead or erratic speedometer, wrong shift points, no lockup and limp mode.
Likely causes (most common first)
- Defective output speed sensor
- Corroded or loose sensor connector, water in the plug
- Chafed or broken wiring in the transmission harness
- Metal shavings on the sensor tip or a damaged tone ring
- Signal interference from a poor ground or a nearby high current cable
- Faulty transmission control module
Can you drive with it?
Driving is possible but risky: cruise control and speedometer may fail and shifts can be harsh, so repair it soon.
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