Inspection Procedure

HINT:

If DTCs P0115, P0116, P0117, P0118 and P0125 are output simultaneously, ECT 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. Freeze frame data records 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, and other data from the time the malfunction occurred.

1. CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0125) 

   Result: 

   Fig 1: Display DTC Output Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT:

   If any other codes besides 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. INSPECT THERMOSTAT (See  INSPECTION  ) 

   Check the valve opening temperature of the thermostat.

   OK: Valve opening temperature is 80 to 84°C (176 to 183°F) 

   HINT:

   Also check that the valve is completely closed under opening temperature as above.

   1. NG: REPLACE THERMOSTAT (See  REPLACEMENT  ) 
   2. OK: Go to next step. 
3. CHECK COOLING SYSTEM (See  ON-VEHICLE INSPECTION  ) 

   Check for defects in the cooling system that might cause the system to be too cold, such as abnormal radiator fan operation or a modified cooling system.

   1. NG: REPAIR OR REPLACE COOLING SYSTEM 
   2. OK: REPLACE ECT SENSOR