Network, generic

U0014 Medium Speed CAN Communication Bus (+) High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0014 means CAN-High of the medium-speed bus lies above its normal range, most often because the (+) wire touches battery voltage. On a differential CAN of the high-speed type this is a fault the network rides through: onsemi and NXP found frames still being delivered, but with shifted levels, reduced noise margin and higher current draw in the transceivers. NXP calls such a short hidden because only transceivers with built-in diagnosis notice it. On the comfort bus the result tends to be subtle: an occasional unresponsive switch, a flickering display or a stored code without complaint. No manufacturer documents U0014 publicly, and Saab's description shows only the two-wire terminated layout that makes this analogy plausible. A CAN-High reading close to battery voltage with ignition on confirms the short.

Likely causes

Medium-speed CAN-High rubbing against a supply wire
Moisture in a door or roof connector linking CAN-High to plus
Aftermarket device wired to the comfort bus incorrectly

Symptoms

  • Occasional unresponsive switches or flickering displays
  • Stored code without obvious malfunction

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 high wiremodule connector

Related codes

U0005U0010U0012U0013

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