U0026
Low Speed CAN Communication Bus (-) High
Communication network (CAN bus)
Generic OBD-II
Medium
What it means
U0026 means the CAN-low (negative) wire of the low-speed communication bus is reading higher than normal, typically from an open circuit, a short to power, or a failing module. The low-speed bus mainly links body and comfort modules, so this fault usually shows up as warning lights and features that stop working rather than an engine problem.
Medium
Can I keep driving? Usually drivable — the low-speed bus mostly carries body and comfort features — but expect warning lights and some functions to stop working until it's fixed.
Common symptoms
What you'll notice
- Warning lights on and body or comfort features not working
- Modules on the low-speed CAN bus stop responding to a scan tool
- Intermittent electrical faults that come and go
- Features like lighting, HVAC, or convenience controls behaving erratically
Common causes
Most likely first
- Short to power or an open on the CAN-low wire pulling bus voltage highLikely
- Chafed, pinched, or corroded CAN bus wiring or connectorsCommon
- A failing module holding the bus at the wrong voltageCommon
- Water intrusion or corrosion at a connector or splice packLess 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 ones are unreachable to map where the fault is on the bus.
- Check battery voltage and charging; correct low voltage, then clear and re-test.
- Inspect the low-speed CAN wiring and connectors for damage, corrosion, or water intrusion.
- Measure CAN-low voltage and bus resistance to find the short or open.
- Disconnect modules one at a time to find one holding the bus high; replace the confirmed faulty module or repair the wiring.
FAQ
Quick answers
Is it safe to drive with U0026?+
Generally yes, since the low-speed bus mostly handles comfort and body features, but get it checked as a bus fault can spread to other systems.
Can I just clear U0026?+
You can, but it comes back unless the wiring fault or failing module is fixed. Rule out a weak battery first, as low voltage can set it.
Related codes
Often seen with U0026
Read & clear U0026 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