OBD-II code · Network
U0073 Control Module Communication Bus "A" Off
A control module has detected that the communication bus is non-functional and has shut its bus interface off. Affects multiple modules at once because none can communicate; on most vehicles the dashboard lights up with several warning lamps simultaneously.
Is it safe to drive with U0073?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyCAN line shorted to supply or ground
- PossibleTerminating resistor failed
- PossibleOne failing module pulling the bus down
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
- 1–8 h
- Emissions test
- Usually unaffected
- Parts involved
- Can Bus Wiring, Can Terminating Resistor, Control Module
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.