DTC P1258 (LUJ)
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 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
| • |
DTCs P0116, P0117, P0118,
P0128 are not set. |
| • |
The engine is operating for
greater than 30 s. |
| • |
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
136°C (277°F) for greater than 1 s.
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, if equipped, may display a message. |
Conditions for Clearing the DTC
DTC P1258 is a Type A DTC.
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Engine Control Module Scan Tool Information for scan tool
information
Circuit/System Verification
| 1. |
If DTC P0480, P0481, P0691,
P0692, P0693, or P0694 is set, diagnose that DTC first.
|
| 2. |
Observe the engine coolant
level. The engine coolant level should be within the operating
range. Refer to Capacities, Approximate Fluid, and Engine Coolant
in the Owner's Manual. |
| 3. |
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. |
| 4. |
Inspect the cooling system for
the following: |
| |
• |
Kinked or pinched hoses,
especially at the radiator |
| |
• |
Loose, missing, or damaged
radiator air seals or deflectors |
|
Note: A small delay
occurs before the ECM changes the cooling fan speed.
|
| 5. |
Command the cooling fans ON
and OFF, low and high speed. The engine cooling fans should turn ON
and OFF with each command. |
Circuit/System Testing
| 3. |
Inspect the water pump and
coolant flow for correct operation. |
| 4. |
Inspect the engine mechanical
for worn, leaking, cracked cylinder heads or engine block.
|
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
|
