Vehicle Communication Bus B (+) High
What it means
U0041 means the CAN-High (+) line of communication bus B is reading abnormally high voltage, usually from a short to a power feed or a module driving the line high. Bus "B" is defined by the manufacturer, so the effect depends on which network it is — anything from lost comfort features to reduced power if it's a powertrain bus. A full module scan shows which segment dropped off and points to the wiring or module at fault.
Can I keep driving? Often drivable, but expect warning lights and lost features; if bus B carries powertrain data on your vehicle it can also cause reduced power, so confirm with a scan.
Common symptoms
What you'll notice
- Multiple modules reporting communication faults at once
- Warning lights and features tied to bus B not working
- Erratic or dead gauges/displays on affected modules
- Possible reduced power if bus B is a powertrain network
Common causes
Most likely first
- CAN-High (+) wire shorted to battery voltage or another power feedLikely
- Damaged or corroded connector on the bus B circuitCommon
- Chafed wiring contacting a power sourceCommon
- A failed module driving the bus voltage highLess often
How to diagnose & fix
Work through it in order
- Scan all modules; the ones that dropped off point to the affected segment of bus B.
- Back-probe CAN-High and CAN-Low and compare to spec to confirm the high-voltage fault.
- Inspect the bus B wiring for chafing or shorts to a power feed, and check connectors for corrosion.
- Disconnect suspect modules one at a time to see if the bus normalizes, isolating a failed module.
- Repair the short or replace the faulty module, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0041?+
Can I just clear U0041?+
Related codes
Often seen with U0041
Read & clear U0041 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.