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Diagnose/P0126
P0126Low SeverityEngine

Insufficient Coolant Temperature for Stable Operation

What This Means

The engine coolant temperature is not reaching or maintaining a stable operating temperature, affecting overall engine efficiency and emission control.

Common Symptoms

  • Slow warm-up
  • Poor heater output
  • Increased fuel consumption
  • Check engine light on

Common Causes

  • Stuck-open thermostat
  • Faulty ECT sensor
  • Cooling system leak
  • Radiator fan relay issue
  • Thermostat housing crack

Estimated Repair Cost

$75 – $350
Parts and labor (varies by vehicle and location)
Difficulty:Easy

Need This Fixed?

Find certified mechanics near you who can diagnose and repair P0126.

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For informational purposes only. Diagnostic trouble codes are starting points for diagnosis, not definitive answers. Always consult a certified mechanic for proper diagnosis and repair. Estimated costs vary by vehicle, location, and shop rates.