VALVE AS-SHUTOFF 5G2944 - Caterpillar

Which Generate This Code:The ECM detects the following condition:
The aftercooler temperature is greater than 88 °C (190 °F) for 4 seconds.
The diagnostic codes 279-03 and 279-04 are not active.System Response:The ECM will log the event. The warning is deactivated if the temperature decreases below 84 °C (183 °F) for 2 seconds.
None
There may be a problem with the aftercooler.
There may be a problem with the aftercooler temperature sensor.Test Step 1. Check for Diagnostic Codes.
Connect ET to the service tool connector.
Turn the keyswitch to the ON position. The engine should be OFF.
Check for any Active Diagnostic Codes or Logged Diagnostic Codes.Expected Result:There should be no diagnostic codes that are present.Results:
OK - There are no diagnostic codes that are present. Proceed to Test Step 2.
Not OK - There are diagnostic codes that are present.Repair: Repair the diagnostic codes that are present. Refer to the appropriate topic in the "Troubleshooting With a Diagnostic Code" section of this manual. Ensure that the repair eliminates the problem. Stop.Test Step 2. Perform a Check of the Cooling System.
Perform a check of the cooling system. Refer to Troubleshooting, "Coolant Temperature is Too High" for possible causes.Expected Result:There are no problems with the cooling system.Results:
OK - There may be an intermittent problem.Repair: Monitor the operation of the engine. Repair the problem. Ensure that the repair eliminates the problem. Stop.
Not OK - There is a problem with the cooling system.Repair: Repair the problem. Ensure that the repair eliminates the problem. Stop.