U0005
High Speed CAN Communication Bus (+) High
Communication network
Generic OBD-II
High
What it means
U0005 means the voltage on the high-speed CAN bus positive wire is reading too high — usually a short to voltage or a module dragging the bus up. The CAN bus is how control modules talk to each other, so a fault here can disable several systems at once and lead to a no-start, stalling, warning lights, or limp mode. Treat it as a priority diagnosis.
High
Can I keep driving? Risky — a shorted high-speed CAN bus can knock modules offline and cause a no-start, stalling, or limp mode; diagnose before relying on the vehicle.
Common symptoms
What you'll notice
- Multiple warning lights at once (check-engine, ABS, airbag, traction)
- No-start or stalling
- Several modules won't communicate with a scan tool
- Erratic gauges or limp mode
Common causes
Most likely first
- CAN bus (+) wire shorted to voltageLikely
- Damaged or chafed CAN harness or connectorCommon
- A failed module dragging the bus highCommon
- Corroded or backed-out connector pinsLess often
- Water intrusion into a connector or moduleLess often
How to diagnose & fix
Work through it in order
- Scan all modules and note which ones are offline.
- Inspect CAN wiring for shorts to power and physical damage; measure CAN(+)/CAN(-) voltages and bus resistance.
- Disconnect modules one at a time to find one pulling the bus high.
- Repair the shorted wiring or replace the faulty module.
- Clear the codes and confirm all modules communicate.
FAQ
Quick answers
Is it safe to drive with U0005?+
Not until it's diagnosed. A high-speed CAN fault can take multiple modules offline, causing no-start, stalling, or loss of safety systems like ABS.
Can I just clear U0005?+
It returns as soon as the bus fault reappears; the shorted wiring or failed module must be found and repaired.
Related codes
Often seen with U0005
Read & clear U0005 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