Network, generic

U0053 Vehicle Communication Bus C (-) High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U0053 reports too much voltage on the (-) conductor of Vehicle Communication Bus C, meaning CAN-Low if Bus C is built as a high-speed CAN, and NXP's TJA1041 application note states that a short of CAN-Low either to battery or to the 5 V transceiver supply makes communication impossible, while onsemi's measurements show the transmitting node stuck in endless failed attempts. All Bus C members go quiet together. A fault-tolerant low-speed bus separates the two cases: the TJA1055 data sheet treats CAN-Low at 5 V as a failure it simply tolerates, but at battery voltage it switches off its CAN-Low driver after a delay and receives over CAN-High alone. No manufacturer documents U0053 publicly. With the ignition on, CAN-Low near 5 V or battery voltage against ground confirms the fault.

Likely causes

(-) wire of Bus C touching a battery or 5 V feed
Moisture in a connector bridging the (-) wire to a supply pin
Damaged transceiver holding CAN-Low high

Symptoms

  • All functions on Bus C drop out at once (high-speed type)
  • Lost-communication codes in modules on other networks
  • Warning lamps or fallback modes depending on the affected modules

Repair estimate

DifficultyHardWorkshop job
Parts and labour€60–800
Time1–5 h

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

Parts involved

bus c wiringcan transceiver

Related codes

U0044U0046U0050U0051U0052

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