Troubleshooting

DTC P0128 THERMOSTAT MALFUNCTION



CIRCUIT DESCRIPTION

DTC Detecting condition:

If the water temperature doesn't get 75 °C (167 °F) even after warning up, it is abnormal.

Steps 1 - 2:

INSPECTION PROCEDURE

HINT: Read freeze frame data using LEXUS hand-held tester or OBD II scan tool, as freeze frame data 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