Network, generic

U0037 Vehicle Communication Bus B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U0037 is the umbrella code for Vehicle Communication Bus B, the second neutral network slot after Bus A; each maker decides which network sits behind it, and published uses differ widely. Volkswagen's 2014 Touareg data book sets it when a CAN frame sent on Bus B goes unacknowledged. FCA calls U0037-00 the LIN bus on the 2018-22 Jeep Wrangler, where it came with U0121 and an intermittent ABS lamp caused by a loose ground point G907A. Volvo's brake control module 2 stores U003700 alongside ECM code P25A268 and a lit check-engine lamp on 2017-24 models; software 3.0.3 cures it. On GM's 2026 full-size SUVs and Silverado/Sierra EV the brake module's U0037-88 procedure is swapped with U0028-88, and Ford reflashes the Mustang GTD dynamics module over false U0037 entries.

Likely causes

Loose or corroded ground or supply of a module on Bus B (FCA: ground G907A)
Module software misreporting or mishandling the bus (Volvo BCM2, Ford VDM, GM brake module 2026)
Damaged bus wiring or a poorly seated connector
A module on Bus B that has stopped answering

Symptoms

  • Warning lamps of the systems on Bus B, e.g. ABS lamp (Jeep) or check-engine lamp (Volvo)
  • Stop/start or chassis functions unavailable
  • Lost-communication codes stored alongside

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–900
Time0.5–5 h

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

Parts involved

bus b wiringbus b nodes

Related codes

U0028U0038U0039U0045U0046U0121

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.