OBD-II code · Network
U0008 High Speed CAN Communication Bus (-) High
The CAN-Low signal is held above its valid range, typically because of a short to battery voltage on the CAN-L wire. Bus communication is lost for every node sharing this segment.
Is it safe to drive with U0008?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyCAN-Low shorted to battery voltage
- PossibleChafed harness against power wire
- 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
- 1–6 h
- Emissions test
- Usually unaffected
- Parts involved
- Can Low Wire, Module Connector
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.