OBD-II code · Powertrain (generic)
P0816 Downshift Switch Circuit
The TCM detects an electrical fault on the manual downshift request switch circuit.
Is it safe to drive with P0816?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySwitch contacts failed
- PossibleWiring open
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
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Downshift Switch, Wiring Harness
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.