P0812: Reverse Input Circuit
What to do
Reverse still works mechanically, but things that depend on the car knowing you are reversing may not — lamps, parking sensors, the camera. If the reversing camera has stopped appearing, that is the same fault rather than a separate electrical problem.
What this code means
The signal telling the module that reverse has been selected is missing or implausible. On a manual transmission this normally comes from a switch on the gearbox; on an automatic it comes from the range sensor.
What depends on it is broader than the gearbox. Reverse selection is what wakes the reversing lamps, the parking sensors and the reversing camera, and on many vehicles it also softens or disables features that make no sense in reverse. So the reported symptom is often not a transmission complaint at all — it is a camera that no longer appears when reverse is selected.
Likely causes
Start here
- Faulty reverse light switch · easy
- Open circuit in switch wiring · moderate
Less common
- Faulty transmission range sensor · moderate
- Corroded or loose connector · easy
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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