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P2184

Engine Coolant Temperature Sensor 2 Circuit Low

ECT sensor 2 reads below lower plausibility — short to ground. The engine coolant temperature sensor feeds warm-up enrichment, fan control and closed-loop entry — a stuck-cold reading keeps the engine in open loop and rich forever.

  • Check engine light: Yes
  • Emissions related: Yes
  • Repair difficulty: medium

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.

  • Short to groundCommon
  • Connector pins corroded - high contact resistanceLess likely
  • Harness chafing through insulationLess likely

Parts involved

  • Engine Coolant Temperature Sensor 2

P2184 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.