TERMINAL 2487959 - Caterpillar

Use this procedure in order to troubleshoot a high differential temperature across the catalytic converter. Also, use this procedure if one of the following diagnostic codes is active. Refer to Troubleshooting, "Diagnostic Trouble Codes" for information about diagnostic trouble codes. Access the engine monitoring system on Caterpillar Electronic Technician (ET) in order to view the current trip points for these engine events. For information on the engine monitoring system, refer to Troubleshooting, "Engine Monitoring Parameters".
Table 1
Engine Events
J1939 Code and Description Conditions which Generate the Code System Response
4779-0 Aftertreatment #1 Three Way Catalyst Differential Gas Temperature : High - most severe (3) The differential temperature across the catalytic converter is above the trip point for the programmed delay time. The code is logged.
The red stop lamp is illuminated.
The engine is shut down.
4779-15 Aftertreatment #1 Three Way Catalyst Differential Gas Temperature : High - least severe (1) The code is logged.
The amber warning lamp is illuminated. Probable Causes
Incorrect engine timing
Engine misfireRecommended Actions
Incorrect Engine Timing
Engine timing that is excessively retarded can affect exhaust temperatures and coolant temperatures.Verify that the timing is correct. Refer to Testing and Adjusting, "Ignition Timing - Adjust" for the correct timing calibration procedure.Engine Misfire
An engine misfire allows unburned gas into the exhaust system. The excess gas can be burned in the inlet of the catalytic converter. High exhaust temperature at the inlet of the catalytic converter will result.Check the engine for a misfire condition. Refer to Troubleshooting, "Engine Misfires, Runs Rough or Is Unstable" for details.