Troubleshooting

CIRCUIT DESCRIPTION

P0128:

If the water temperature becomes 75 °C (167 °F) or more, it is abnormal.

If not due to the thermostat malfunction it is abnormal.

Steps 1 - 2:

INSPECTION PROCEDURE

HINT: Read freeze frame data using TOYOTA hand-held tester or OBD II scan tool. Because freeze frame records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.