Circuit Description
The powertrain control module (PCM) or engine control module (ECM) 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 128°C (262°F). When an over temperature condition is present, DTC P1258 will set. The PCM or ECM will disable 2 groups of cylinders by turning OFF the fuel injectors. By switching between the 2 groups of cylinders, the PCM or ECM is able to reduce the temperature of the coolant.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1258 Engine Coolant Overtemperature - Protection Mode Active
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The PCM or ECM detects an engine metal over temperature. |
| • | The above condition is present for at least 8 seconds. |
Action Taken When the DTC Sets
| • | The PCM or ECM illuminates the malfunction indicator Lamp (MIL) when the diagnostic runs and fails. |
| • | The driver information center (DIC), if equipped may display a message. |
Conditions for Clearing the MIL/DTC
| • | The PCM or ECM will turn the MIL OFF after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC Last Test Failed clears when the diagnostic runs and passes. |
| • | Use a scan tool in order to clear the MIL and the DTC. |
Step | Action | Yes | No |
|---|---|---|---|
Connector End View Reference: Cooling System Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Check the engine cooling fans for proper operation. Are the engine cooling fans operative? | Go to Engine Overheating | |
