Inspection Procedure

HINT:

• If DTC P0115, P0116, P0117, P0118 and P0125 are output simultaneously, engine coolant temperature sensor circuit may be open or short. Perform the troubleshooting of DTC P0115, P0117 or P0118 first.
• Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data record the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data 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, as well as other data from the time when a 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 OBD II scan tool main switch ON.
   3. When using hand-held tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO/CURRENT CODES.

   CHECK: 

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

   RESULT: 

   Fig 1: DTC Output Reference Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT:

   If any other codes besides "P0125" are output, perform the troubleshooting for those DTCs first.

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

   CHECK: 

   Check that there is detect cooling 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.