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Home >> Toyota >> 2001 >> Prius >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P0116: Engine Coolant Temperature Sensor Circuit Range/Performance >> Diagnosis & Repair
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Diagnosis & Repair

  1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0116 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and then retest.
  2. Remove and inspect cooling system thermostat for damage and proper operation. Thermostat is located behind thermostat housing which is located just below the intake manifold.
  3. If thermostat is defective, replace thermostat. Ensure proper cooling system bleeding procedure is performed when filling cooling system. See COOLING SYSTEM BLEEDING under COOLING SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article. If thermostat is okay, replace ECT sensor. Manufacturer states that converter and inverter assembly must be removed for servicing of ECT sensor. The converter and inverter assembly are involved with the high-voltage system used on this vehicle and service procedure should only be performed by authorized dealer.
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