Troubleshooting

DTC P0128 Thermostat Malfunction

DTC Detection Condition:

CIRCUIT DESCRIPTION
If the water temperature doesn't reach 75 °C (167 °F) even after warming up, it is abnormal.

Step 1 - 2:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the 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.