P0128

DTC P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

DESCRIPTION

DTC Detection Condition:

HINT: This is the purpose of detecting the "thermostat" malfunction.

If the engine coolant temperature (ECT) does not reach 75 °C (167 °F) despite sufficient warm-up time has elapsed.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

Component Operating Range:

The ECM estimates the engine coolant temperature (ECT) based on engine starting temperature, engine loads and engine speed. The ECM then compares the estimated ECT with the actual ECT. When the estimated ECT reaches 75 °C (167 °F), the ECM checks the actual ECT. If the actual ECT is less than 75 °C (167 °F), the ECM will interpret this as a fault in the thermostat or the engine cooling system and set a DTC.

MONITOR RESULT
Refer to detailed information. Checking Monitor Status

INSPECTION PROCEDURE

HINT: Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.