Network, generic

U0011 Medium Speed CAN Communication Bus Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

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.

Likely causes

Loose or corroded connector on the medium-speed pair
Low battery voltage or poor ground causing module resets
Module software miscounting or missing messages (update needed)

Symptoms

  • Comfort functions such as windows, locks or climate controls work intermittently
  • Code stored as history in body modules

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–700
Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

can bus wiringbody control module

Related codes

U0002U0010U0012U0015

References: saabwisonline.com, static.nhtsa.gov, saabwisonline.com.