OBD-II code · Powertrain (generic)
P0812 Reverse Input Circuit
General electrical fault on the reverse-engagement input — the signal that tells the TCM (and other modules — backup lights, parking sensors) that the gear lever is in Reverse. With the input invalid backup lights and rear sensors do not activate.
Is it safe to drive with P0812?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen or shorted reverse input wire
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Reverse Input Switch, Wiring Harness
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.