Diagnostic Instructions
DTC Descriptor
DTC P1258: Engine Coolant Overtemperature - Protection Mode Active
Circuit/System Description
The engine control module (ECM) uses the engine coolant temperature (ECT) sensor to monitor the engine for an over-termperature condition. This condition occurs when the coolant temperature is above a calibrated value for a calibrated length of time. The
ECM will disable half of the cylinders by turning OFF the fuel injectors. By disabling half of cylinders, the ECM is able to reduce the temperature of the coolant.
Conditions for Running the DTC
• | DTC P0116, P0117, P0118, or P0128 are not set. |
Conditions for Setting the DTC
Coolant temperature more than 131°C (267.8°F) for more than 7 seconds.
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 instrument panel (IP) will illuminate the coolant indicator lamp and the driver information center (DIC), if equipped, may display a message. |
Conditions for Clearing the DTC
DTC P1258 is a type A DTC.
Reference Information
Description and Operation
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Important: If DTC P1482 is set, diagnose that DTC first.
- Observe the engine coolant level. The engine coolant level should be within operating range. Refer to Capacities - Approximate Fluid, and Engine Coolant in the Owner's Manual.
- Ensure that the vehicle has the correct engine coolant, with correct concentration, and is not old, contaminated or contains additives. Refer to Recommended Fluids and Lubricants in the Owner's Manual.
- Inspect the cooling system for the following:
• | Kinked or pinched hoses, especially at the radiator |
• | Loose, missing, or damaged radiator air seals or deflectors |
Important: A small delay occurs before the ECM changes the cooling fan speed.
- Command the cooling fan in both low and high speed.
⇒ | Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. |
Circuit/System Testing
- Test the thermostat for correct operation. Refer to
Thermostat Diagnosis.
- Test the engine cooling system for overheating. Refer to
Engine Overheating.
- Inspect the water pump and coolant flow for correct operation. Refer to
Water Pump Replacement.
- Inspect the engine mechanical for worn/leaking/cracked cylinder heads and engine block. Refer to
Coolant in Combustion Chamber and
Coolant in Engine Oil for the 4.4L engine, or
Coolant in Combustion Chamber and
Coolant in Engine Oil for
the 4.6L engine.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.