P0C04: motor B overcurrent is filtered through two protective paths

P0C04 is the motor B phase-current overcurrent code in GM's table. The monitor is designed to protect inverter switching devices from excessive current indications. It does not use the same conditions as the individual current-sensor high-range checks.

Identify which event pattern matters

The threshold is a U, V or W phase-current report greater than 600 A. GM defines a fast repeated-event path with two qualifying counts among ten, and a slower intermittent path with five counts among fifty. The printed task rate is 2.08 ms for both.

The wakeup signal must be on, and the source lists one-trip reporting. A useful diagnostic record therefore includes the phase measurements and event pattern, not just one current number observed long after the fault was recorded.

Separate protection from root-cause diagnosis

The protective code does not determine which component caused the excessive report. Companion current-sensor range or correlation faults should be retained so a technician can assess measurement integrity before attributing the event to a physical motor or inverter defect.

The table does not supply a universal repair, component test or permissible workshop current. Do not reproduce the threshold by forcing load. A qualified hybrid technician must use the actual vehicle's diagnostic information and high-voltage precautions, then verify credible current behavior and the relevant monitor outcome after the cause has been established.

Source and applicability

GM 2010 10OBDG10 Hybrid Diagnostics, cited BPCM or hybrid-controller monitor only. Historical calibration values are not universal specifications; no per-code model, engine or hardware fitment has been established. GM PDF, physical page 296.