Diagnostic Aids
WARNING: This page is about a different car, the 2003 Cadillac Seville and 2003 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
- A DTC P0128 is designed to detect a faulty thermostat.
- Excessive coolant flow through the bypass hose to the throttle body may cause this DTC to set.
- A skewed ECT sensor may cause a P0128 to set.
- A skewed IAT sensor may cause this DTC to set.