P0128-Thermostat Rationality: Notes
- When Monitored : With the engine running.
- Set Condition : The PCM predicts a coolant temperature value that it will compare to the actual coolant temperature. If the two coolant temperature values are not within 10°C (18°F) of each other, this DTC is set.
| Possible Causes |
|---|
| LOW COOLANT LEVEL |
| THERMOSTAT OPERATION |
| ENGINE COOLANT TEMPERATURE SIGNAL CIRCUIT SHORT TO VOLTAGE |
| ENGINE COOLANT TEMPERATURE SIGNAL CIRCUIT OPEN |
| ENGINE COOLANT TEMPERATURE SIGNAL CIRCUIT SHORT TO GROUND |
| ENGINE COOLANT TEMPERATURE SIGNAL CIRCUIT SHORT TO SENSOR GROUND CIRCUIT |
| SENSOR GROUND CIRCUIT OPEN |
| ENGINE COOLANT TEMPERATURE (ECT) SENSOR |
| POWERTRAIN CONTROL MODULE |
For a complete Powertrain Control Module Circuit Diagram, refer to SCHEMATICS AND DIAGRAMS .