Network, generic

U0006 High Speed CAN Communication Bus (-) Open

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U0006 points to an interrupted CAN-Low conductor, i.e. the (-) line on the high-speed network. That line rests near 2.5 V and sinks by about a volt whenever a dominant bit is sent. Nodes isolated by the break no longer receive a usable differential signal from the rest of the network, while the modules still joined on both wires can go on exchanging data. A line interruption is outside what common high-speed transceivers can diagnose themselves (NXP), so the code relies on module-specific checks such as missing acknowledgements. No manufacturer documents U0006 publicly. Frequent findings are a conductor fractured at a door or tailgate hinge, a backed-out terminal or a corroded splice. With the battery disconnected, a check across the two lines often shows about twice the normal 60 ohms when the break separates one of the terminators.

Likely causes

CAN-Low conductor fractured at a hinge or flex point
Corroded splice or connector in the CAN-Low path
CAN-Low terminal backed out after work on the harness

Symptoms

  • Part of the modules unreachable, others still respond
  • Warnings from the affected systems, sometimes only when moving doors or harness

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–800
Time1–6 h

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

Parts involved

can low wiremodule connector

Related codes

U0001U0003U0007U0008

References: nxp.com, saabwisonline.com, ti.com.