Network, generic

U0052 Vehicle Communication Bus C (-) Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0052 signals a ground short on the (-) line of Vehicle Communication Bus C; where Bus C follows the high-speed CAN layout, the affected line is CAN-Low, and NXP's application note for the TJA1041 lists this short among the hidden bus failures: nodes keep communicating, so a controller only learns of it from a transceiver with bus diagnosis. Such a transceiver needs at least four dominant phases of 4 µs or more on the wire before its failure flag is valid, and it reliably catches shorts between 0 and 50 ohms. The price of the fault is a smaller noise margin; with high bus capacitance dominant periods can stretch until bit timing is violated. The vehicle therefore usually drives normally and the code appears in a single module. No manufacturer documents U0052 publicly. Battery off, CAN-Low shows practically zero ohms to chassis.

Likely causes

(-) wire of Bus C chafed against body metal
Harness trapped under a trim panel or seat rail
Transceiver in one module pulling CAN-Low to ground

Symptoms

  • Often no noticeable symptom, code found during a scan
  • Occasional brief warning from a module on Bus C

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

U0043U0046U0049U0051U0053

References: nxp.com, onsemi.com, law.cornell.edu.