P0720: the gearbox output speed sensor circuit has a fault
The output speed sensor tells the gearbox computer how fast the shaft leaving the gearbox is turning, which it compares against the input speed to work out exactly what each gear is doing. This code means the electrical circuit for that sensor isn't behaving the way the computer expects. It covers the wiring and connector as much as the sensor itself.
You might notice
- The gearbox may shift harshly, hesitate to change gear, or hold a gear longer than it should
- The engine warning light comes on
- output speed sensor
- — a sensor that tells the gearbox computer how fast the shaft leaving the gearbox is turning
- gearbox computer
- — the separate computer, distinct from the engine control unit, that runs an automatic gearbox
What the code itself says
P0720 is a powertrain (engine, gearbox and drive system) code, and the 0 after the letter means it is a generic code with a standard meaning.
Grouped here as: Gearbox control — Gear selection, shift quality, fluid condition and the sensors and solenoids the gearbox's own control module reads. That grouping is ours, to help explain the code. The code's official family is the letter at the start.
This page is generic. Your car isn't.
A code on its own only tells you what the sensor saw, not what's actually wrong — and that changes next to your other codes. Read this one together with the rest of your scan and we'll work out what's really going on.
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