Diagnostic trouble code (DTC) information ECM-201A

Condition 

During the engine warm-up phase, the way the temperature increases is checked. This is compared with the expected temperature increase, calculated for example according to load conditions and starting temperature.

The diagnostic trouble code (DTC) is stored if the engine control module (ECM) registers that the measured engine coolant temperature (ECT) deviates too much from a calculated temperature.

The diagnostic trouble code (DTC) can be diagnosed with the engine running and at operating temperature, after the engine has first been allowed to cool from operating temperature for at least 8 hours.

Substitute Value 

• None.

Possible Source 

• Damaged thermostat.

Fault symptom[s] 

• Malfunction indicator lamp (MIL) lit
• The engine does not become warm.