Network, generic

U0007 High Speed CAN Communication Bus (-) Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0007 reports that the (-) line CAN-Low on the fast bus is held below its valid band, normally by a short to ground. The physical layer copes with this particular case: onsemi recorded ongoing transmission with a distorted level pattern and raised transceiver current, and NXP counts it among the hidden failures. Traffic therefore continues, yet the reserve against interference shrinks, which may surface as an occasional lost frame or a brief warning. Only modules whose transceiver offers bus diagnosis can spot the condition directly. No manufacturer documents U0007 publicly; FCA field cases describe ground shorts on the CAN C (+) and (-) lines under U0001. Inspect sections near sheet-metal edges, brackets and seat rails, then measure CAN-Low to ground with the battery disconnected.

Likely causes

CAN-Low insulation worn through against body metal
Water in a connector bridging CAN-Low to a ground pin
Module transceiver internally shorted on its CAN-Low pin

Symptoms

  • Usually no noticeable malfunction, code found during a scan
  • Occasional short-lived warnings, worse with moisture

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–800
Time1–5 h

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

Parts involved

can low wirecan transceiver

Related codes

U0001U0004U0006U0008

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