U0059 Vehicle Communication Bus D (+) High
U0059 means the (+) line of Vehicle Communication Bus D sits at too high a voltage, typically from contact with a battery or 5 V feed. On a high-speed CAN layout the line concerned is CAN-High, and the fault belongs to the shorts NXP calls hidden: communication goes on, and only a transceiver with bus diagnosis can report it. NXP's TJA1041 note mentions a further side effect, namely that the bus wake-up logic of that device was designed so that a CAN-High short to battery does not wake the network while it goes to sleep; a hint that such a short can otherwise interfere with the network going to sleep. Fault-tolerant low-speed hardware like the TJA1055 handles it in two timed steps and ends on CAN-Low alone. No manufacturer documents U0059 publicly. Measured against ground, CAN-High sitting near supply voltage settles the diagnosis.
Likely causes
Symptoms
- Usually no symptom, code found during a scan
- Occasional single warning from a module on Bus D
Repair estimate
Typical range across vehicles; the real cost depends on what the testing finds.