Circuit Description
The powertrain control module (PCM) uses the 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 2 groups of 4 cylinders by turning OFF the fuel injectors. By switching between the 2 groups of cylinders, the PCM is able to reduce the temperature of the coolant.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The PCM detects an engine metal over temperature. |
| • | The above condition is present for at least 8 seconds. |
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 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 Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF after 3 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 | Did you perform the Engine Cooling Diagnostic System Check? | Go to Step 2 | |
2 | Inspect the engine cooling fans for proper operation. Are the engine cooling fans operative? | Go to Engine Overheating | |
