GEAR-SUN 2768185 - Caterpillar

Probable Causes
Operation with a light load
Diagnostic codes from the Exhaust Temperature Scanner
Low temperature from the cylinder exhaust ports
Faulty exhaust temperature sensor
Diagnostic codes for the ignition system
Faulty ignition
Low cylinder compressionRecommended Repairs
Operation with a Light Load
Operation with a low load can result in low exhaust temperatures. Operate the engine at low idle or near low idle in order to identify a misfire problem.Troubleshoot the cause of the misfire. Refer to Troubleshooting, "Engine Misfires, Runs Rough or Is Unstable".Diagnostic Codes from the Exhaust Temperature Scanner
Use the Caterpillar Electronic Technician (ET) to check for diagnostic codes that relate to the thermocouples. Troubleshoot the code.Low Temperature from the Cylinder Exhaust Ports
Observe the temperatures for the exhaust ports of the cylinders in the suspect bank.If any of the temperatures for the exhaust ports are significantly different, determine the reason for the difference in the exhaust port temperatures. Make repairs, as needed.Faulty Exhaust Temperature Sensor
Observe the temperatures from the thermocouples for the turbocharger(s) after the engine is shut off.When the engine is operating properly, the temperatures from similar locations are reduced at a similar rate. Also, the temperatures from similar locations are comparable.If any discrepancies are found, switch the suspect thermocouple for another thermocouple. If the temperature problem follows the thermocouple, replace the thermocouple.If the temperature problem stays at the original location of the thermocouple, investigate the cause for the low temperature.Diagnostic Codes for the Ignition System
Use Cat ET to check for diagnostic codes that relate to the ignition system. Troubleshoot the code.Faulty Ignition
Inspect the components of the ignition system for the suspect cylinder bank. Refer to Troubleshooting, "Ignition Secondary - Test".Make repairs, as needed.Low Cylinder Compression
Measure the cylinder pressures of the suspect bank in order to check for problems that are related to compression.If low compression is found, investigate the cause of the low compression. Make repairs, as needed.