Powertrain, generic · Hybrid propulsion

P0C55 Drive Motor B Position Sensor Circuit A

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0C55 is the general circuit code for the first pickup winding (Circuit A) of the resolver on the second traction motor. It applies when the motor B controller recognises a fault on that winding but cannot assign it to a low or high level. No manufacturer documents this code publicly. GM, which runs two motors in the Volt, ELR and the two-mode trucks, files motor B winding faults under P0C57 and P0C58 instead. Compared with P0A45, which reports the motor B angle signal as a whole, P0C55 narrows the search to one winding and its two wires. CARB requires such circuit faults to be detected separately from out-of-range faults. The result is usually a warning lamp and the loss of motor B for drive or charging.

Likely causes

Open wire or loose terminal in the motor B Circuit A lines
Damaged or corroded motor B resolver connector
Defective first pickup winding in the motor B resolver

Symptoms

  • Check engine lamp with hybrid system warning
  • Motor B unavailable, reduced propulsion
  • Engine may run more often because the second motor is offline

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–2,500
Time1–6 h

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

Parts involved

drive motor b position sensor awiring harnesshybrid control module

Related codes

P0C56P0C57P0C58P0C59P0C5FP0A45

References: law.cornell.edu, gsi.ext.gm.com, en.wikipedia.org.