U0017 means the medium‑speed CAN bus is detected as stuck at a high voltage level (bus‑high condition). This usually results from a short to battery voltage, a faulty transceiver, or damaged wiring that forces the bus dominant/recessive level incorrectly.
A wire harness short to +12 V pulls the CAN line high, causing the bus‑high condition. This is the most common cause of U0017.
A defective transceiver (e.g., in the body‑control module, instrument cluster, or gateway) can continuously drive the bus high, mimicking a short to power.
Water intrusion, chafing, or a bent pin can create an intermittent short to voltage on the CAN pair, triggering the fault.
Exposure to moisture or abrasion can compromise insulation, allowing the CAN wires to contact a power source and raise the bus voltage.
Less frequently, a faulty ECU may lock its CAN output dominant, which the bus interprets as a high‑voltage condition.
A defect in the PCM/ECM’s CAN controller can falsely report a bus‑high, but this is rare and should be considered only after wiring and node checks.
No. The PCM/ECM is rarely the cause of a bus‑high condition. Wiring shorts, faulty transceivers, or damaged connectors are far more common; the PCM should only be considered after those have been ruled out.
A malfunctioning charging system can cause voltage spikes, but U0017 specifically indicates a short to voltage on the CAN lines, not a general system overvoltage. Addressing the charging system alone will not fix a CAN‑bus short.
Driving may be possible, but loss of communication with safety‑related modules (ABS, stability control, etc.) can occur, leading to warning lights and reduced vehicle functionality. It is advisable to diagnose and repair the issue promptly.