OBD-II code · Powertrain (generic)
P0864 TCM Communication Circuit Range/Performance
The Transmission Control Module communication circuit reports a communication circuit range/performance fault. Data exchange between TCM and ECM is impaired.
Is it safe to drive with P0864?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyCommunication bus fault
- PossibleTCM internal 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
- Tcm, Wiring Harness, Ecm
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.