Circuit Description
To reduce the engine temperature, the powertrain control module (PCM) has the ability to disable a number of fuel injectors during an engine over-temperature condition. The PCM considers the engine over temperature whenever the engine coolant temperature (ECT) reaches 129.4°C (264.92°F) for more than 10 seconds. This type A DTC sets, to show that the PCM detected an over-temperature condition and that the system engaged the protection mode.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
DTC P1258 Engine Coolant Overtemperature - Protection Mode Active
Conditions for Running the DTC
| • | DTCs P0116, P0117, P0118, P0125, P0128, P1114 or P1115, are not set. |
| • | The engine is running. |
Conditions for Setting the DTC
The ECT reaches 129.4°C (264.92°F) or higher 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 disable selected 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. |
Diagnostic Aids
| • | If an overheating condition exists, repair the overheat condition and change the engine oil and filter. |
| • | Using the Freeze Frame/Failure Records data may aid in locating an intermittent condition. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or fail. Operate the vehicle within the same Freeze Frame condition (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. |
| • | For an intermittent, refer to Testing for Intermittent Conditions and Poor Connections . |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Cooling Schematics Connector End View Reference: Cooling System Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Select the DTC Failed This Ignition option using the scan tool. Does the scan tool display any DTCs related to the engine coolant temperature (ECT) sensor that you have not diagnosed? | ||
