2012 Toyota Prius TwoFACTORY OEM SERVICE PROCEDURE

DTC P0116: Engine Coolant Temperature Circuit Range / Performance Problem: Procedure

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0116) 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
    5. Read the DTCs.

      Result

      Result Proceed to
      DTC P0116 is output A
      DTC P0116 and other DTCs are output B

      HINT: 

      If any DTCs other than P0116 are output, troubleshoot those DTCs first.

    B → See step   3 

    A: Go to next step 

  2. INSPECT WATER INLET WITH THERMOSTAT SUB-ASSEMBLY 
    1. Remove the water inlet with thermostat sub-assembly. Refer to REMOVAL .
    2. Measure the valve opening temperature of the water inlet with thermostat sub-assembly.

      Standard value

      80 to 84°C (176 to 183°F)

      HINT: 

      In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.

    NG → See step   4 

    OK → See step   5 

  3. GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART 
  4. REPLACE WATER INLET WITH THERMOSTAT SUB-ASSEMBLY. Refer to  REMOVAL 
  5. REPLACE ENGINE COOLANT TEMPERATURE SENSOR. Refer to  REMOVAL 
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.