Network, generic

U009E Vehicle Communication Bus J Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U009E flags unreliable traffic on Vehicle Communication Bus J without a total loss. No manufacturer publishes a use of U009E. Interference is a likely source. Texas Instruments names fluorescent lamps, switching power supplies and motor drives as typical emitters of common-mode noise that couples onto bus lines, and explains that a receiver without good rejection may take it for data. A twisted pair and differential signalling keep this in check, so opened twists or retrofitted electronics near the harness are suspects. NXP adds that tolerated wiring faults also worsen electromagnetic behaviour. Where messages go unacknowledged, Wikipedia notes that nodes often resend them repeatedly, which can drive them into the error-passive state.

Likely causes

Interference from nearby loads or retrofitted electronics
Bus wires untwisted at a repair
Loose contact in a Bus J connector

Symptoms

  • Short dropouts on Bus J, often with certain loads switched on
  • Warnings that appear briefly and clear

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–800
Time0.5–5 h

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

Parts involved

bus j wiringmodule connector

Related codes

U007CU0093U009CU009D

References: ti.com, nxp.com, en.wikipedia.org.