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 132°C (270°F). When an over temperature condition is present, DTC P1258 will set. The PCM will alternately disable 4 injectors. By alternately disabling 4 injectors, the PCM is able to reduce the temperature of the coolant.
DTC Descriptors
This diagnostic procedure supports the following DTC:
P1258 Engine Coolant Overtemperature - Protection Mode Active
Conditions for Running the DTC
| • | DTC's P0117, P0118, P1114, and P1115 are not active. |
| • | The engine is running. |
Conditions for Setting the DTC
| • | The ECT is above 132°C (270°F). |
| • | The condition is present for more than 10 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 instrument panel cluster (IPC) to turn ON the MIL indicator. |
| • | The PCM will alternately disable 2 groups of 4 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 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 |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 | Check the engine cooling fan for proper operation. Does the engine cooling fan operative properly? | Go to Engine Overheating |
