OBD-II code · Powertrain (generic)
P085A Gear Shift Control Module B Communication Circuit
The gear shift control module B communication circuit reports a communication circuit condition. Shift command exchange is impaired.
Is it safe to drive with P085A?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyCommunication lost
- PossibleWiring fault
- Less likelyGateway module routing CAN messages incorrectly
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
- 1–5 h
- Emissions test
- Usually unaffected
- Parts involved
- Gear Shift Control Module B, Wiring Harness
Related codes
- P0860Gear Shift Control Module A Communication Circuit
- P0857Traction Control Input Signal Range/Performance
- P0858Traction Control Input Signal Low
- P0859Traction Control Input Signal High
- P085BGear Shift Control Module B Communication Circuit Low
- P085CGear Shift Control Module B Communication Circuit High
- P085DGear Shift Control Module A Performance
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.