Circuit Description
The powertrain control module (PCM) uses the engine coolant temperature (ECT) sensor to monitor the engine for an over temperature condition. This condition occurs when the coolant temperature is above 131°C (268°F). When an over temperature condition is present, DTC P1258 will set. The PCM will disable two groups of four cylinders by turning OFF the fuel injectors. By switching between the two groups of cylinders, the PCM is able to reduce the temperature of the coolant.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
The PCM detects an engine over temperature condition.
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test has been run and failed. |
| • | The PCM will signal the instrument panel cluster (IPC) to turn ON the Service Engine Soon indicator. |
| • | The PCM will alternately disable two groups of four cylinders by turning OFF the fuel injectors. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and File Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF after three consecutive trips that the diagnostic has been run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. |
Step | Action | Yes | No |
|---|---|---|---|
Connector End View Reference: Cooling System Connector End Views | |||
1 | Was the Diagnostic System Check for Engine Cooling performed? | Go to Step 2 | |
2 | Check the engine coolfans for proper operation. Are the engine coolfans operative? | Go to Engine Overheating | |
