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P1622 – Engine Coolant Thermostat Fault

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Symptoms

  • Overheating
  • Poor heater output

Causes

  • Stuck thermostat
  • Low coolant
  • Sensor issue

Diagnosis

  • Check coolant temp
  • Inspect thermostat
  • Check coolant level

Repair

  • Replace thermostat
  • Refill coolant
  • Replace sensor
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