U0014 indicates that the voltage on the Medium Speed Controller Area Network (CAN) High circuit is stuck higher than expected, typically due to a short to voltage or an internal module fault. This bus usually connects body-control modules such as the instrument cluster, HVAC controller, or door modules, not the powertrain. The code sets when the control module detects an abnormal voltage level on the CAN (+) line during communication attempts.
The CAN High wire may be chafed against the frame or power feed, or pinched in harness routing, causing it to short to battery voltage or intermittently ground out. This is the most common physical fault for bus-high codes.
Water intrusion into connectors at the instrument cluster, HVAC module, or other body modules can wick into the pins and create high-resistance paths or shorts, distorting bus voltage.
A faulty door module, climate control head, or other body computer may have a damaged CAN transceiver that pulls the High line to an incorrect voltage level, disrupting communication for the entire bus.
A broken wire or backed-out pin in the CAN High line can cause signal reflections or voltage levels that the receiving modules interpret as a bus-high fault.
Although the PCM usually resides on the High Speed CAN bus rather than the Medium Speed bus, a rare internal failure of a gateway function—if the PCM bridges the networks—could theoretically disrupt the MS-CAN High line. This is an extremely unlikely cause and should only be considered after wiring and all other modules are ruled out.
No. U0014 concerns the Medium Speed CAN bus used primarily for body electronics, and the PCM is almost never the root cause. Replacing the PCM is usually an incorrect diagnosis; technicians should verify wiring harnesses and body modules first.
Generally yes, for short periods. This fault typically affects convenience features like climate control or displays rather than engine operation, though some systems may operate erratically or not at all.
The underlying electrical fault—such as a wire shorted to battery voltage or a module with an internal short—remains physically present. The code will reset until the circuit is repaired or the faulty module is replaced.
While voltage spikes during improper jump-starting can damage module transceivers, the code itself indicates a specific circuit fault, not merely a temporary voltage event. If the code appeared after battery work, inspect for disturbed wiring or connectors first.