U0026 code meaning
Low Speed CAN Communication Bus (-) High
What U0026 means
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.
U0026 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0026
- Often no noticeable effect
- Occasional comfort function dropouts when the bus runs on one wire
Common causes of U0026
- Most likelyCAN-Low chafed against a battery or ignition feed
- PossibleMoisture in a connector linking CAN-Low to a supply pin
- Less likelyFaulty transceiver driving CAN-Low to its supply
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Low speed CAN wiringCAN low wire
What each part of U0026 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 26 | The exact fault in that area. |
What to do next
- Note U0026 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0026
What does U0026 mean?
U0026 means "Low Speed CAN Communication Bus (-) High". U0026 means CAN-Low, the (-) line of a two-wire low-speed CAN, is held too high. It is a generic code, so it means the same on every make.
Is it safe to drive with U0026?
U0026 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0026 fail an emissions test?
U0026 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U0026 to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U0026 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.