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P2D2C

Engine Coolant Temperature Measurement System - Multiple Sensor Correlation

The signals of multiple engine coolant temperature sensors do not correlate within the calibrated tolerance. One sensor drifts or installation offset between channels.

  • Check engine light: Yes
  • Emissions related: No
  • Repair difficulty: easy

Symptoms

  • Check engine light on
  • Cooling fan runs constantly or not at all
  • Cabin heater weak or excessively hot
  • Possible long warm-up time or hard cold start

Common causes

Ordered by how often each turns out to be the cause.

  • One sensor characteristic driftedCommon
  • Harness incorrectly swapped between channelsPossible

Parts involved

  • Engine Coolant Temperature Sensor 1
  • Engine Coolant Temperature Sensor 2
  • ECM

P2D2C is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.