SENSOR GP-POSITION 1761605 - Caterpillar

Table 1
Event Code    
J1939 Code    Code Description    Comments    
3609-17     DPF #1 Intake Pressure : Low - least severe (1)     The inlet pressure at the Diesel Particulate Filter (DPF) is low.
There are no faults for the DPF intake pressure sensor.
There are no faults on the 5V sensor supply.
There are no faults for the battery voltage.
There are no faults for the DPF inlet temperature.    
3609-18     DPF #1 Intake Pressure : Low - moderate severity (2)     The inlet pressure at the Diesel Particulate Filter (DPF) is very low.
There are no faults for the DPF intake pressure sensor.
There are no faults on the 5V sensor supply.
There are no faults for the battery voltage.
There are no faults for the DPF inlet temperature.
A factory password is required to reset this code.    
Test Step 1. Check for Active Diagnostic Codes
Connect the electronic service tool to the diagnostic connector.
Turn the keyswitch to the ON position.
Download the following items before performing any troubleshooting or clearing any diagnostic codes:
Warranty Report
Aftertreatment Regeneration Trigger History
Product Status Report with Histograms
Use the electronic service tool to check for active diagnostic codes.Expected Result:One of the diagnostic codes listed in Table 1 is active.Results:
One of the preceding diagnostic codes is active. - Proceed to Test Step 2
None of the preceding diagnostic codes are active. - The fault appears to be resolved.STOPTest Step 2. Inspect the Exhaust System for Leaks
Inspect the exhaust system for leaks between the exhaust manifold and the Clean Emissions Module (CEM).
Check the exhaust system for loose connections or open ports.Results:
The exhaust system has leaks. - Repair: Perform the following procedure:
Repair any faults in the exhaust system.
Use the electronic service tool to perform an ARD Ignition Test.Note: The ARD Ignition Test cannot be performed if the DPF soot loading is above 80%. When the DPF soot loading is above 80%, use the electronic service tool to perform a Manual DPF Regeneration.
Confirm that the fault has been eliminated.STOP
The exhaust system does not have leaks. - Proceed to Test Step 3.Test Step 3. Inspect the Diesel Particulate Filter
Remove the DPF. Refer to Disassembly and Assembly, "Diesel Particulate Filter - Remove".
Inspect the DPF for missing sections or damage.Results:
The DPF has a damaged or missing section. - Repair: Perform the following procedure:
Replace the damaged DPF. Refer to Disassembly and Assembly, "Diesel Particulate Filter - Install".
Use the electronic service tool to perform an ARD Ignition Test.Note: The ARD Ignition Test cannot be performed if the DPF soot loading is above 80%. When the DPF soot loading is above 80%, use the electronic service tool to perform a Manual DPF Regeneration.
Confirm that the fault has been eliminated.STOP
The DPF is not damaged. - Repair: Install the DPF. Refer to Disassembly and Assembly, "Diesel Particulate Filter - Install".Contact the technical communicator at a Caterpillar dealer.STOP