U0046
Vehicle Communication Bus C
Communication network (CAN bus)
Generic OBD-II
Medium
What it means
U0046 is a general fault on vehicle communication Bus C, meaning a module detected a problem with this data bus that lets control modules share information. It usually surfaces as warning lights and modules that won't respond to a scan tool. Which features are affected depends on what "Bus C" carries on your specific vehicle.
Medium
Can I keep driving? Usually drivable, but a bus fault can drop several modules offline at once — expect warning lights and reduced features until it's diagnosed.
Common symptoms
What you'll notice
- One or more warning lights on across different systems
- Modules on Bus C stop responding to a scan tool
- Intermittent electrical features dropping out and returning
- Loss of specific functions carried on this bus
Common causes
Most likely first
- Open, short, or high resistance in the Bus C wiring or connectorsLikely
- Chafed, pinched, or corroded bus wiringCommon
- A failing module disrupting the busCommon
- Water intrusion or corrosion at a connector or spliceLess often
- Weak battery or low system voltage setting spurious network codesLess often
How to diagnose & fix
Work through it in order
- Scan every module and note which are unreachable to locate the fault on Bus C.
- Check battery voltage and charging; correct low voltage, then clear and re-test.
- Inspect Bus C wiring and connectors for damage, corrosion, or water intrusion.
- Measure bus voltages and resistance to find an open, short, or bad termination.
- Isolate modules one at a time to find a unit disrupting the bus; repair the wiring or replace the confirmed faulty module.
FAQ
Quick answers
Is it safe to drive with U0046?+
Often yes for short trips, but because a bus fault can disable systems you rely on, have it diagnosed before extended driving.
Can I just clear U0046?+
You can, but it returns unless the underlying wiring fault or failing module is repaired. Check the battery first, as low voltage can trigger it.
Related codes
Often seen with U0046
Read & clear U0046 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX