RING-RETAINING 7N2171 - Caterpillar

Event E021Conditions Which Generate This Code:The Electronic Control Module (ECM) detects the following condition:
Exhaust inlet temperature is greater than the default temperature of 750 °C (1382 °F) for five seconds.
The engine has been running for three seconds.
The diagnostic codes CID-FMI 827-08 and CID-FMI 828-08 are not active.System Response:The event is logged. The ECM derates the engine at 15 second intervals in 2% increments when the exhaust inlet temperature is above 750 °C (1382 °F) for 5 seconds. The fuel limiting function will continue until the exhaust temperature returns below 740 °C (1364 °F) or until the maximum derate has been reached. After the temperature returns below 740 °C (1364 °F) the derate due to a high exhaust temperature will be deactivated.Possible Performance Effect:
Low powerTroubleshooting:
There may be an exhaust restriction.
There may be an air leak.Test Step 1. Check for "ACTIVE" Diagnostic Codes.
Start the Caterpillar Electronic Technician (ET).
Turn the main power to the ON position.
Check for any active diagnostic codes or logged diagnostic codes. Expected Result:No diagnostic codes are present.Results:
OK - No diagnostic codes are present. Proceed to Test Step 2.
Not OK - Diagnostic codes 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.STOPTest Step 2. Perform a Check of the Cooling System.
Perform a check of the exhaust system. Refer to the diagnostic procedure Troubleshooting, "Exhaust Temperature is Too High" for possible causes. Expected Result:There are no problems with the exhaust system.Results:
OK - There are no problems with the exhaust system. 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 exhaust system.Repair: Repair the problem. Ensure that the repair eliminates the problem.STOP