Network, generic

U0015 Medium Speed CAN Communication Bus (-) Open

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0015 stands for a break in CAN-Low, the (-) conductor of the medium-speed CAN. Modules separated by the break stop exchanging data with the rest of the network, whereas units still connected on both wires keep working; which functions disappear therefore depends on where the line is cut. Ford's F-Super Duty bulletin shows how a single open connector in the MS-CAN switches off the HVAC controls, the front switch panel and the headlamp function together. Common high-speed transceivers cannot diagnose a line interruption themselves (NXP), so the code results from the module's own reasoning about missing replies. No manufacturer documents U0015 publicly. Wiring that moves, such as door, tailgate and seat harnesses, and connectors opened during body or upfit work are the first places to check.

Likely causes

CAN-Low conductor fractured in a moving harness section
Connector not reconnected after body or upfit work
Corroded CAN-Low splice

Symptoms

  • Only some comfort functions lost, depending on break location
  • Fault varies when doors or seats are moved

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–600
Time0.5–4 h

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

Parts involved

can low wiremodule connector

Related codes

U0006U0010U0012U0016

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