Diagnostic Instructions
DTC Descriptor
DTC P1258: Engine Coolant Over temperature - Protection Mode Active
Circuit/System Description
The powertrain control module (PCM) 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 PCM will disable half of the cylinders by turning OFF the fuel injectors. By disabling half of cylinders, the PCM is able to reduce the temperature of the coolant.
Conditions for Running the DTC
• | DTC P0117 or P0118 is not set. |
Conditions for Setting the DTC
Coolant temperature more than 132°C (270°F) for greater than 10 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 engine coolant temperature indicator lamp, if equipped, will illuminate. |
• | 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
- 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 |
Circuit/System Testing
- Test the thermostat for correct operation. Refer to
Thermostat Diagnosis .
- Test the fan clutch for proper operation. Refer to
Fan Clutch 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 for worn/leaking/cracked cylinder heads and engine block. Refer to
Coolant in Combustion Chamber and
Coolant in Engine Oil .
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.