U0011 code meaning
Medium Speed CAN Communication Bus Performance
What U0011 means
U0011 says the medium-speed CAN is running but not dependably: expected periodic messages come late or not at all, error frames accumulate, or a node briefly goes bus-off and rejoins. No manufacturer publicly documents U0011 in its J2012 sense with thresholds. The nearest model is GM's high-speed counterpart U0002, where a supervised message missing for more than 250 ms sets the code. Alfa Romeo even assigns the number to something else: in the Giulia and Stelvio drive style control module, U0011-14 and U0011-15 mark a faulty down circuit of the DNA rotary selector. Typical causes are loose or corroded connectors, water ingress, voltage dips during cranking and module software. Body and comfort functions then work only intermittently while the car itself drives normally.
U0011 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 U0011
- Comfort functions such as windows, locks or climate controls work intermittently
- Code stored as history in body modules
Common causes of U0011
- Most likelyLoose or corroded connector on the medium-speed pair
- PossibleLow battery voltage or poor ground causing module resets
- PossibleModule software miscounting or missing messages (update needed)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
CAN bus wiringBody control module
What each part of U0011 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 11 | The exact fault in that area. |
What to do next
- Note U0011 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 U0011
What does U0011 mean?
U0011 means "Medium Speed CAN Communication Bus Performance". U0011 says the medium-speed CAN is running but not dependably: expected periodic messages come late or not at all, error frames accumulate, or a node briefly goes bus-off and rejoins. It is a generic code, so it means the same on every make.
Is it safe to drive with U0011?
U0011 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0011 fail an emissions test?
U0011 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 U0011 to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will U0011 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.