Network, generic

U0016 Medium Speed CAN Communication Bus (-) Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0016 reports CAN-Low of the medium-speed bus, the (-) wire, sitting below its valid range, typically through a short to ground. Transferred from the high-speed physical layer, which Saab's two-wire terminated mid-speed GMLAN resembles, this is a fault the bus tolerates: onsemi measured continuing transmission with deformed levels, and NXP files it as a hidden failure visible only to transceivers with diagnosis. The comfort network therefore usually keeps working, but becomes more sensitive to interference; drivers rarely notice anything beyond sporadic glitches. No manufacturer documents U0016 publicly. Because the fault hides so well, the code itself is often the only clue; measure CAN-Low against ground with the battery disconnected and follow the harness near sharp edges.

Likely causes

Medium-speed CAN-Low chafed against a ground point or sheet edge
Water ingress in a footwell or door connector
Comfort module transceiver internally shorted on CAN-Low

Symptoms

  • Usually no lasting malfunction, code found during a scan
  • Sporadic glitches in comfort functions

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–600
Time1–4 h

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

Parts involved

can low wirebody control module

Related codes

U0007U0010U0015U0017

References: onsemi.com, nxp.com, saabwisonline.com.