OBD-II code · Network
U0304 Invalid Data Received from Transmission Control Module
The ECU receives messages from the TCM but their content is implausible (e.g. invalid gear, impossible speed). The transmission may switch to limp-home mode and shift quality is degraded.
Is it safe to drive with U0304?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- PossibleSoftware version mismatch after replacement
- PossibleTCM partially failing
- Less likelyGateway module routing CAN messages incorrectly
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–6 h
- Emissions test
- Usually unaffected
- Parts involved
- Tcm, Can Bus Wiring
Related codes
- U0301Software Incompatibility with ECM/PCM
- U0302Software Incompatibility with TCM
- U0303Software Incompatibility with Transfer Case Control Module
- U0305Software Incompatibility with Cruise Control Module
- U0306Software Incompatibility with Fuel Injector Control Module
- U0307Software Incompatibility with Glow Plug Control Module
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.