Network, generic

U0088 Vehicle Communication Bus F (-) Shorted to Bus F (+)

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

With U0088 the two conductors of Vehicle Communication Bus F are bridged to each other. Signalling on both FlexRay and CAN rests on the difference between the wires, so with them joined there is none: a FlexRay receiver such as NXP's TJA1081B sees a difference below its activity threshold and treats the line as idle, while every sending node reads back something other than what it transmits and sets its bus error flag. On a single channel this ends all exchange on Bus F, which is why modules elsewhere then log the silent partners as lost. Volvo names a short between CAN-High and CAN-Low as one cause of U008088 on its truck datalink 7. For CAN, onsemi's bench tests likewise show a bridged pair stopping all traffic. Isolate sections by unplugging connectors while measuring between the wires.

Likely causes

Bus F pair crushed so both wires touch
Water or corrosion bridging both wires in a splice or connector
Transceiver with an internal short between its bus pins

Symptoms

  • Complete loss of the functions served by Bus F
  • Lost-communication codes for several modules

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–1,000
Time1–6 h

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

Parts involved

bus f wiringmodule connector

Related codes

U0072U0080U0082U0085

References: nxp.com, onsemi.com, static.nhtsa.gov, law.cornell.edu.