OBD-II code · Network
U0070 Communication Bus "B" Performance
The secondary communication bus (Bus B, often a chassis or comfort sub-bus) shows reduced performance — high error rate, intermittent dropouts, or framing errors. Bus is still alive but unreliable.
Is it safe to drive with U0070?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyMarginal wiring or corroded connector
- PossibleEMI interference (aftermarket equipment)
- 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
- 1–5 h
- Emissions test
- Usually unaffected
- Parts involved
- Can Bus Wiring, Can Terminating Resistor
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.