Diagnostic Aids
WARNING: This page is about a different car, the 2002 Pontiac Grand Prix, 2002 Chevrolet Malibu, and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
- DTC P0128 is designed to detect a faulty thermostat.
- A skewed ECT sensor may cause a DTC P0128 to set.
- If a DTC P0125 and DTC P0128 are both set, a skewed ECT sensor is the most likely cause.
- A skewed Intake Air Temperature (IAT) sensor may cause this DTC to set.