The powertrain control module (PCM) uses the engine coolant temperature (ECT) sensor to monitor the engine for an over temperature condition. When an over temperature condition is present, DTC P1258 will set.
• | A P1258 fault is enabled. |
• | The PCM has performed the coolant temperature check. |
The PCM has disabled the fuel injectors.
Step | Action | Yes | No |
---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Check the engine cooling fans for proper operation. Are the engine cooling fans operative? | Go to Engine Overheating |
• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of the diagnostic category. |
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.
• | The engine is running for greater than 30 seconds. |
• | DTC P0116, P0117, P0118, or P0128 are not set. |
The EM detects that engine coolant temperature is greater than 136°C (277°F) for more than 1 second or a cumulative time of 10 seconds.
• | 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. |
DTC P1258 is a Type A DTC.
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Important: If DTCs P0480, P0481, P0691, P0692, P0693, or P0694 are set, diagnose those DTCs first.
• | Cooling system leaks |
• | Kinked or pinched hoses, especially at the radiator |
• | Loose, missing, or damaged radiator air seals or deflectors |
• | The radiator and A/C condenser for any air flow obstructions or bent fins--Refer to Symptoms - Engine Cooling . |
Important: A small delay occurs before the ECM changes the cooling fan speed.
⇒ | If the cooling fans do not operate in both speeds, refer to Cooling Fan Inoperative . |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.