P1258

DTC P1258

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P1258
- Engine Coolant Overtemperature - Protection Mode Active

Circuit/System Description

The engine control module (ECM) uses the engine coolant temperature sensor to monitor the engine for an over-temperature condition. This condition occurs when the coolant temperature is above a calibrated value. The ECM will alternately disable 2 groups of cylinders by turning OFF the fuel injectors. By switching between the 2 groups of cylinders, the ECM is able to reduce the temperature of the coolant.

Conditions for Running the DTC

* The engine is operating for greater than 30 seconds.

* DTC P1258 runs continuously once the conditions above have been met.

Conditions for Setting the DTC

The ECM detects that engine coolant temperature is warmer than 132°C (270°F) for 2 seconds or greater.

Action Taken When the DTC Sets

* DTC P1258 is a Type A DTC.

* The engine will operate in the Overheated Engine Protection Operating Mode.

* The IP will illuminate the coolant temperature indicator lamp and the driver information center (DIC), if equipped, may display a message.

* If the protection mode is active and an ECT sensor DTC sets, the protection mode will remain active at the start of the next drive cycle until the ECT sensor DTC runs and passes.

Conditions for Clearing the MIL/DTC

DTC P1258 is a Type A DTC.

Reference Information

Schematic Reference

Engine Controls Schematics (LFX) [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views Fuel Pump and Level Sensor Assembly

Description and Operation

* Cooling Fan Description and Operation Cooling Fan

* Instrument Cluster Description and Operation Instrument Cluster

* Indicator/Warning Message Description and Operation Indicator/Warning Message

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Engine Control Module Scan Tool Information Scan Tool Testing and Procedures for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify DTC P0480, P0691, or P0692 is not set.

• If a DTC is set
Refer to DTC P0480, P0481, P0691, P0692, P0693, or P0694 P0480.

• If no DTCs is set

Note: A short delay occurs before the ECM changes the cooling fan speed.

3. Verify the cooling fan operates at each available speed as commanded with a scan tool.

• Cooling fan does not operate
Refer to Cooling Fan Inoperative Cooling Fan Inoperative.

• Cooling fan operates

4. Verify that the engine does not overheat.

• Engine overheats
Refer to Engine Overheating Engine Overheating.

• Engine does not overheat

5. Operate the vehicle within the conditions that the customer experienced and verify the DTC does not set.

• If the DTC sets
Refer to Symptoms - Engine Cooling Symptoms - Engine Cooling.

• If the DTC does not set

6. All OK

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.