OBD-II code · Powertrain (generic)
P0899 Transmission Control System MIL Request Circuit High
Voltage on the transmission control system MIL request circuit is above the expected window. Wire shorted to B+ or driver open.
Is it safe to drive with P0899?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyWire shorted to B+
- PossibleDriver fault open
- Less likelyConnector pins corroded - high contact resistance
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
- Best left to a mechanic
- Typical labour
- 0.5–2 h
- Emissions test
- Usually unaffected
- Parts involved
- Mil Request Circuit, Tcm
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.