COUPLING 9T0642 - Caterpillar

The Electronic Control Module (ECM) detects an abnormal difference in pressure between the atmospheric pressure and the turbocharger inlet pressure. Information on default settings and ranges for this event can be found in Troubleshooting, "Event Codes".System Response:The ECM logs the event code.Possible Performance Effect:172(1)
There are no performance effects.172(2)
The engine power will be derated.Troubleshooting:Test Step 1. Check for Restrictions in the Air Inlet System
Inspect the air filter for restrictions and/or clogging. Clean the air filter or replace the air filter.
Check the air inlet piping for restrictions and for damage. Refer to Systems Operation/Testing and Adjusting. Expected Result:The air filter was cleaned or the air filter was replaced. No restrictions have been found in the air inlet system.Results:
OK - The air filter and the air inlet system are OK.Repair: If an electrical problem with the sensor is suspected, refer to the diagnostic functional test Troubleshooting, "Engine Pressure Sensor Open or Short Circuit - Test".STOP
Not OK - There is a problem with the air filter and/or the air inlet system.Repair: Clean the air filter or replace the air filter, if necessary. Repair any damage that has been found with the air inlet system.STOP