U0026Low Speed CAN Communication Bus (-) High
- Generic OBD-II code · Network
- How the car detects it
- U0026 means CAN-Low, the (-) line of a two-wire low-speed CAN, is held too high. Since this wire already sits near 5 V at rest in an ISO 11898-3 network, the outcome depends on where the short goes. Against the 5 V supply (failure 6a in NXP's TJA1055) the transceiver stays in differential mode with normal drivers and termination. Against battery voltage (failure 6) its comparator trips after roughly 0.3 to 1.6 ms, the CAN-Low driver is switched off, the termination becomes a weak pull-up and reception continues over CAN-High alone. Either way the bus normally survives, which is why the code is often found without a clear complaint. No manufacturer documents U0026 publicly, and the GM low-speed GMLAN gets by with one conductor. Look for chafing against a feed wire or water in a connector.
- What you may notice
- Often no noticeable effect
- Occasional comfort function dropouts when the bus runs on one wire
- Likely causes
- LikelyCAN-Low chafed against a battery or ignition feed
- PossibleMoisture in a connector linking CAN-Low to a supply pin
- RareFaulty transceiver driving CAN-Low to its supply
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.