P0720: Output speed sensor: circuit fault
The control unit is not getting a valid signal from the sensor measuring rotation at the gearbox output; the speedometer and shifts may suffer.
| Code | P0720 |
|---|---|
| System | Engine and transmission |
| Group | P07xx, Transmission |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P0720 means
The output speed sensor measures how fast the shaft leaving the gearbox towards the wheels is turning. The control unit uses it to decide when to shift and, on many cars, it also feeds the speedometer or other systems. This code indicates a general electrical fault in its circuit.
Most common causes
- Loose, corroded or oily sensor connector
- Damaged sensor wiring, often near hot or moving parts
- Metal particles stuck to the sensor
- Faulty sensor
- Transmission control unit fault (uncommon)
Symptoms
- Speedometer failing, flickering or dropping to zero
- Harsh or oddly timed shifts
- Gearbox stuck in one gear (limp mode)
- Engine or gearbox warning light on
Can you drive with P0720?
With care You can drive with care, but the gearbox usually locks into one gear and acceleration suffers. Get it to a garage soon and avoid long trips like this.
How to check it
Check whether the speedometer works properly: if it fails at the same time as the code appears, it points to the output sensor or its wiring. On the scanner you can compare the vehicle speed reading with a GPS.
How to read and clear P0720 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0720 with this same explanation and whether it’s confirmed, pending or permanent.
This code is usually stored by the gearbox control unit. With Free you read it for nothing with its short description, because Free reads every control unit; with Pro you also get the full explanation, how the car was running when it was logged and clearing.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.
Similar codes
- P0714 Transmission fluid temperature sensor: circuit intermittent
- P0715 Input/turbine speed sensor: circuit fault
- P0716 Input/turbine speed sensor: range/performance
- P0717 Input/turbine speed sensor: no signal
- P0721 Output speed sensor: range/performance
- P0722 Output speed sensor: no signal
- P0725 Engine speed input to gearbox: circuit fault
- P0729 Incorrect gear ratio in sixth gear
- P0700 Transmission control system: fault detected
- P0701 Transmission control system: range/performance
- P0702 Transmission control system: electrical fault
- P0703 Torque converter/brake switch B: circuit fault
P0720 is a generic code, so it means the same on any make, for example on Alfa Romeo, Dacia, Kia, Nissan, Opel / Vauxhall, Škoda. See what Final OBD does on your car in makes and models.
What does code P0720 mean?
The output speed sensor measures how fast the shaft leaving the gearbox towards the wheels is turning. The control unit uses it to decide when to shift and, on many cars, it also feeds the speedometer or other systems. This code indicates a general electrical fault in its circuit.
Can you drive with P0720?
You can drive with care, but the gearbox usually locks into one gear and acceleration suffers. Get it to a garage soon and avoid long trips like this.
How do you clear P0720?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0720 comes back.
Read it on your car
Final OBD reads the faults of every control unit for free, including each make’s own codes, and with Pro explains each one in plain English. Free clears engine faults at no cost.
Coming soon
Mid to late October 2026
If you want to try it in your car before anyone else, send us your email and we will add you as a tester.
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