ELBOW 2L8228 - Caterpillar

Conditions Which Generate This Code:The Electronic Control Module (ECM) monitors the following parameters in order to calculate the exhaust temperature:
Intake manifold air temperature
Barometric pressure
Engine speedHigh intake manifold air temperature, high altitude operation, and high engine loads can cause the exhaust temperature to increase to a level that may damage the components of the exhaust system. When this occurs, the ECM derates the engine in order to reduce the exhaust temperature. This protects the components of the exhaust system from damage.System Response:The code is logged. Passwords are not required in order to clear the logged code.Engine power is reduced.Test Step 1. Determine the Operating ConditionsInterview the operator, when possible. Determine if the engine was under heavy load or the engine is operating at a high altitude.Expected Result:The event occurred because of normal engine operation.Results:
OK - The event occurred because of normal engine operation. Clear the logged event and return the engine to service.STOP
Not OK - The event should not have occurred. Proceed to Test Step 2.Test Step 2. Check the Air-to-Air Aftercooler (ATAAC)The intake manifold air temperature can increase if the ATAAC is obstructed. Check the fins of the ATAAC for obstructions.Expected Result:The fins of the ATAAC are obstructed.Results:
OK - The fins of the ATAAC are obstructed.Repair: Clean the fins of the ATAAC. Clear the event. Return the engine to service.STOP
Not OK - The fins of the ATAAC are clear of obstructions. Proceed to Test Step 3.Test Step 3. Check the 5 Volt Supply to the Atmospheric Pressure SensorIf the atmospheric pressure sensor is not being powered by the 5 volt supply, the output of the sensor may float to a value that is interpreted by the ECM as a high altitude condition. The ECM receives the erroneous value of altitude and the ECM derates the engine.
Verify that the keyswitch is in the ON position.
Measure the value of the 5 volt supply at the harness connector for the atmospheric pressure sensor.Expected Result:The voltage is approximately five volts.Results:
OK - The supply voltage at the atmospheric pressure sensor is approximately five volts. There are no further troubleshooting procedures for this event. Clear the event and return the engine to service.STOP
Not OK - The supply voltage at the atmospheric pressure sensor is not approximately five volts. There is a problem with the wiring for the 5 volt supply between the atmospheric pressure sensor and the ECM.Repair: Identify the wiring problem and make the necessary repairs.When the 5 volt supply is present at the atmospheric pressure sensor, clear the event and return the engine to service.STOP