The Electronic Control Module (ECM) monitors the following parameters in order to estimate the exhaust temperature:
- Intake manifold air temperature
- Barometric pressure
- Engine speed
High 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:
If equipped, the warning lamp may come on and the event code will be logged.
Engine power is reduced.
Test Step 1. Determine the Operating Conditions
Determine if the engine was under heavy load or the engine is operating at a high altitude.
Expected Result:
The event occurred because of abnormal engine operation.
Results:
- OK - The event occurred because of abnormal engine operation. Clear the logged event and return the engine to service.STOP
- Not OK - The event indicates an engine fault. If the engine is equipped with an air-to-air aftercooler, proceed to Test Step 2.
Test Step 2. Check the Air-to-Air Aftercooler (ATAAC) (if equipped)
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. Refer to the OEM manual for the ATAAC. Return the engine to service.
STOP
- Not OK - The fins of the ATAAC are clear of obstructions.
STOP