Powertrain, generic · Hybrid propulsion

P0C3C DC/DC Converter Temperature Sensor A Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P0C3C covers a signal from DC/DC converter temperature sensor A that drops out or jumps for short moments while staying mostly within range. The heat sink of a converter warms and cools slowly, so fast jumps point to the signal path rather than to real temperature changes. No manufacturer documents P0C3C publicly. The method is known from GM's hybrid tables for comparable thermistors, such as P0C37 for battery sensor F: the controller adds up signal changes in short windows and fails the test when several windows exceed a limit. CARB requires such inputs to be monitored for faults. Typical causes are a loose terminal, vibration damage or moisture at the converter connector. Unlike P0C3A and P0C3B, the fault may vanish between tests, so a wiggle test helps.

Likely causes

Loose terminal or moisture at the converter connector
Harness damaged by vibration with intermittent contact
Intermittent fault inside the converter

Symptoms

  • Intermittent hybrid or EV warning
  • Occasional 12 V charging interruptions

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–2,500
Time0.5–4 h

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

Parts involved

dcdc converter temp sensor awiring harnessdcdc converter

Related codes

P0C38P0C39P0C3AP0C3BP0C41P0E5C

References: law.cornell.edu, gsi.ext.gm.com.