Network, generic

U0050 Vehicle Communication Bus C (+) High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0050 flags excess voltage on the (+) wire of Vehicle Communication Bus C. On a high-speed-style CAN bus, the conductor is CAN-High sitting at battery or 5 V level, a condition onsemi found survivable: frames still pass, the dominant bits merely look different and the transceiver draws about as little as when idle, since its high-side driver delivers no current. NXP therefore lists it with the hidden failures that need transceiver diagnosis to surface at all. Fault-tolerant low-speed transceivers such as NXP's TJA1055 confirm the fault in two timed steps and then fall back to single-wire operation on CAN-Low. Because driving rarely changes, the code is often found by chance during a scan. No manufacturer documents U0050 publicly. CAN-High near supply voltage against ground confirms it.

Likely causes

(+) wire of Bus C touching a battery or 5 V feed
Moisture in a connector linking the bus wire to supply
Aftermarket device tapped into the bus wire

Symptoms

  • Usually no symptom, code found during a scan
  • Occasional single warning from a module on Bus C

Repair estimate

DifficultyHardWorkshop job
Parts and labour€60–700
Time1–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

bus c wiringcan transceiver

Related codes

U0041U0046U0048U0049U0053

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