Inspection Procedure

HINT:

• If DTCs P0115, P0116, P0117, P0118 and P0125 are output simultaneously, the engine coolant temperature sensor circuit may be open or short. Perform the troubleshooting of DTC P0115, P0117 or P0118 first.
• Read freeze frame date using the hand-held tester or the OBD II scan tool. Freeze frame date record the engine conditions when a malfunction is detected. When troubleshooting, freeze frame date can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

1. Are there any other codes (besides DTC P0125) being output? 

   PREPARATION: 

   1. Connect the hand-held tester or the OBD II scan tool to the DLC3.
   2. Turn the ignition switch ON and push the hand-held tester or the OBD II scan tool switch ON.
   3. When using hand-held tester, enter the following menus: DIAGNOSIS/ENHANCED OBD II / DTC INFO / CURRENT CODES.

   CHECK: 

   Read the DTC using the hand-held tester or OBD II scan tool.

   RESULT: 

   Fig 1: Display (DTC Output) Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT:

   If any other codes beside "P0125" is output, perform the troubleshooting for those codes first.

   1. B: Go to relevant DTC chart (see  DIAGNOSTIC TROUBLE CODE CHART   ). 
   2. A: Go to next step. 
2. Check thermostat (See  INSPECTION  ). 
   1. NG: Replace thermostat (See  REMOVAL  ). 
   2. OK: Go to next step. 
3. Check cooling system 

   CHECK: 

   Check that there is defect system which causes over cool, such as abnormal radiator fan operation, modified cooling system and so on.

   1. NG: Repair or replace cooling system. 
   2. OK: Replace engine coolant temperature sensor.