Monitor DTC Status
P0128 Coolant Thermostat (Coolant Temperature below Thermostat Regulating Temperature)
Scantool Diagnostics
Monitor Scantool Data
1. Connect scantool to Data Link Connector (DLC).
2. IG "ON".
3. Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.
4. Read "DTC Status" parameter.
5. Is parameter displayed "Present fault"?