What U0074 means
A control module has shut its bus B interface off because the bus is non-functional.
How the engine computer detects it
Bus B is typically a secondary CAN segment (often body or chassis) and a failure disables all modules connected to it.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
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
Common causes
- Bus B line shorted to supply or ground Most likely
- One failing module pulling the bus down Possible
- Gateway module routing CAN messages incorrectly Less likely
How to diagnose U0074
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: can bus wiring, can terminating resistor, control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Reading the code
- U
- Network
- 0
- Generic (SAE) code
- 074
- Specific fault
Questions drivers ask
Can I drive with code U0074?
It depends on which module stopped communicating. If the car drives normally, drive carefully to a shop. If the engine, transmission, brakes or steering act up, or many warning lights come on at once, stop and have it towed.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.