U0026 indicates that the low‑speed CAN communication bus is seeing a voltage higher than expected, which disrupts data exchange between body‑control modules and other ECUs on that network. The condition is usually caused by a wiring fault, a short to power, or a failing node on the bus rather than the main engine controller.
A wire harness short to battery voltage raises the bus level, triggering the high‑voltage fault. This is the most common cause.
A severed or high‑resistance wire prevents proper termination, causing the bus to float high when the network tries to drive dominant bits.
If one or both 120 Ω resistors are open or changed, the bus impedance is incorrect, leading to abnormal voltage levels.
A malfunctioning ECU (e.g., body control module, gateway) can short the bus internally or fail to release the line, pulling the voltage high.
Oxidation or poor contact increases resistance and can create a voltage offset that appears as a high‑bus condition.
While technically possible, a faulty powertrain control module rarely causes U0026; it should be considered only after all wiring and node checks are exhausted.
No. The PCM/ECM is rarely the cause of a high‑speed CAN bus fault. Wiring, connectors, termination resistors, or a faulty node on the bus are far more likely culprits.
A blown fuse that powers a node on the low‑speed CAN can prevent that module from communicating, which may trigger the code, but the fuse itself does not create the high‑voltage condition. Check fuses as part of the wiring inspection.
Driving may be possible if essential systems (engine, brakes, steering) remain functional, but safety‑related features like airbags, ABS, or stability control could be impaired. Repair the bus fault before relying on those systems.
Clearing the code only removes the stored fault; if the underlying wiring or component issue persists, the code will return shortly after the vehicle is operated.