C4.4 Marine Generator Set Caterpillar

Fuel Filter Is Restricted - Secondary Fuel Filter

Usage:

C4.4 NRP

Note: The following codes are only applicable for engines with a pre-filter pressure sensor.

The Electronic Control Module (ECM) detects an abnormal differential pressure across the active secondary fuel filter.

Use this procedure if one of the following codes is active.

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Table 1
Diagnostic Trouble Codes for a Restricted Secondary Fuel Filter
J1939 Code	Code Description	Comments
95-15	Engine Fuel Filter Differential Pressure : High - least severe (1)	The differential pressure across the active secondary fuel filter is high. No 3510 codes are active. The code is logged.

Probable Cause

Diagnostic codes
Secondary Fuel filter blocked
Sensor

Recommended Actions

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Table 2
Troubleshooting Test Steps	Values	Results
1. Diagnostic Codes A. Connect the electronic service tool to the diagnostic connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Determine if a diagnostic is active or recently logged.	Diagnostic codes	Result: A 95-15 code is present. Proceed to Test Step 2. Result: A 95-15 code is not present. Return the unit to service.
2. Change the Active Fuel Filters A. Replace the active secondary fuel filter. Refer to the Operation and Maintenance Manual, "Fuel System Secondary Filter - Replace". B. Replace the active primary fuel filter. Refer to the Operation and Maintenance Manual, "Fuel System Primary Filter (Water Separator) Element - Replace".	Fuel filter change	Result: The code is no longer active. Use the electronic service tool to clear all logged diagnostic codes and verify that the fault has been eliminated. Return the unit to service. Result: The 95-15 code becomes active after changing the fuel filters. Proceed to Test Step 3.
3. Fuel Pressure Sensors A. Use the electronic service tool to compare the status of the following parameters with the engine not running: · Secondary Fuel Filter Pre-filter Pressure · Secondary Fuel Filter Post-filter Pressure	Fuel pressure sensors	Result: A sensor does not read atmospheric pressure while the engine is not running. Troubleshoot the sensor circuit. Refer to Troubleshooting, "Sensor Signal (Analog Active) - Test". Result: The sensors read atmospheric pressure while the engine is off. Contact the Technical Communicator at a Cat dealer.