U0055
Vehicle Communication Bus D
Data bus (CAN)
Generic OBD-II
Medium
What it means
U0055 is a general fault on Communication Bus D — a module has detected a problem with this data bus but not a specific short or open. Bus D is one of the vehicle's manufacturer-defined networks; when it's disrupted the modules on it can stop exchanging data, causing warning lights and lost features.
Medium
Can I keep driving? Usually drivable for now, but the systems on Bus D may act up or quit and warning lights can appear; have it diagnosed soon.
Common symptoms
What you'll notice
- Warning lights on for one or more systems
- Modules on Bus D dropping off the scan tool
- Intermittent or lost function of Bus D features
- Additional U-codes stored alongside
Common causes
Most likely first
- Damaged or corroded Bus D wiring or connectorLikely
- Water intrusion in a harness connectorCommon
- A failed module disrupting the busCommon
- Loose power or ground to a bus moduleLess often
- Damaged terminating resistorLess often
How to diagnose & fix
Work through it in order
- Scan all modules and record the communication codes.
- Check battery voltage and charging before diagnosing the bus.
- Inspect Bus D wiring and connectors for damage, corrosion, or moisture.
- Measure bus resistance key-off (about 60 ohms on a terminated bus).
- Disconnect modules one at a time to isolate a unit disturbing the bus.
FAQ
Quick answers
Is it safe to drive with U0055?+
Usually yes short-term, but features on Bus D may be unreliable. If systems quit or lights multiply, get it checked.
Can I just clear U0055?+
It returns if the bus fault is still present. Repair the wiring or module first, then clear and retest.
Related codes
Often seen with U0055
Read & clear U0055 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