Network, generic

U0019 Low Speed CAN Communication Bus

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0019 is the general fault slot for the low-speed CAN, the slow body network serving doors, lighting, locks and comfort electronics. Two physical forms exist: the two-wire fault-tolerant CAN of ISO 11898-3, which NXP's TJA1055 runs at up to 125 kBd and keeps alive on one wire after a single break or short, and the one-conductor low-speed GMLAN that GM runs at 33.33 kbit/s. FCA names U0019 CAN B Bus; on the 2015 Ram ProMaster the BCM logged U0019-01 (general electrical failure) with a lit MIL, cured by a BCM reflash under bulletin 08-230-22. Mercedes-Benz lists U001988 among the codes behind false anti-theft alarms in 2019-25 models and has supply, ground and CAN lines to the overhead panel checked. Comfort functions suffer rather than driveability.

Likely causes

Damaged low-speed bus wiring or corroded, loose connector pins
Poor supply or ground at a module on the body bus
Module software logging the code without a real fault (FCA ProMaster BCM)
Faulty module or transceiver disturbing the low-speed bus

Symptoms

  • Comfort functions such as locks, lighting or windows fail or act erratically
  • Anti-theft alarm triggers without obvious reason
  • Lost-communication codes for several body modules
  • MIL on in some vehicles (FCA ProMaster 2015)

Repair estimate

DifficultyHardWorkshop job
Parts and labour€60–900
Time0.5–5 h

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

Parts involved

low speed can wiringbody control modulemodule connector

Related codes

U0001U0010U0020U0021U0024U0027

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