0122678 JOHNSON O-RING, Seat, relief valve

This code occurs when an active regeneration is needed within a 30 minute time frame and this occurs 3 consecutive times.The only way to change this code from active to logged is to perform the “DPF Regeneration Time Interval Reset”. Refer to “CAT ET Service Features” story in this manual for the procedure. Unlike most other engine codes, this code will not stop a regeneration.Note: If the machine is continued to operate with this code active, fuel dilution can occur. Caterpillar recommends to checking the oil level and obtain an oil sample. Change the oil and oil filter if needed.This code should be indicating a DPF that is getting full. However this could be due to a break in the wires for the DPF Differential Pressure Sensor circuit. One of the triggers for an active regeneration is high DPF Differential Pressure. Refer to the “General Information” and “Regeneration Levels of the Diesel Particulate Filter (DPF)” for more information.An intermittent fault in the wiring harness could send a faulty signal to the Engine ECM for a high differential pressure. The intermittent fault can occur without creating a logged coded. The intermittent fault is the most common cause of the 523602-0 code on low hour machines. The code must be investigated thoroughly prior to removing a DPF when this code is present. Contact the local Caterpillar Technical Communicator (TC) prior to removing a DPF when this code is present.If suspected that (523602-0) High Frequency of Regeneration is occurring due to a full DPF, then refer to the machines Operation and Maintenance Manual for the recommended cleaning interval. If the engine hours exceeds the service interval, the DPF should be cleaned.If the engine hours are less than the service interval, then consult your dealer technical communicator (TC) before removing and cleaning the DPF. If the DPF is found full on an engine with hours less than the service interval, then investigate the root cause. These include failures that result in consuming oil, such as a failed turbo or worn cylinders. These would have other symptoms like low engine oil, high oil consumption, oil sample with high wear metals.Other causes are not using Ultra Low Sulfur Diesel or not using low ash engine oil. Refer to the machines Operation and Maintenance Manual for approved engine oils.Note: After making the appropriate repairs, the “DPF Regeneration Time Interval Reset” in CAT ET under the service tab must be performed to change the 523602-0 from an active code to a logged code. Refer to “Cat ET Service Features” for more information. It is always recommended to clear the logged code.Note: If the DPF is cleaned, refer to Special Instruction, REHS7788, "Cleaning the Diesel Particulate Filter (DPF) on C2.4, C3.3B and C3.8 Engines".Probable Causes
Diagnostic codes
Maintenance schedule
Low compression
Injectors
High sulfur fuel
High ash engine oilRecommended Actions
Table 2
Troubleshooting Test Steps Values Results
1. Check for Active or Logged Codes
A. Establish communication with Cat ET.
Codes
Result: Active or logged codes for High and Low Voltages for the DPF Differential Pressure Sensor (3251-3, 3251-4), then this can cause a faulty intermittent high DPF Differential Pressure reading. This will cause the ECM to incorrectly think the DPF is full and will result in more active regenerations, which can cause 52302–0 High frequency Regeneration or Fuel Dilution in a SOS. These -3 or -4 codes are frequently intermittent and typically are a broken wire near the DPF Differential Pressure Sensor connect.
Result: There active or logged codes. Refer to "Sensor Signal (Analog, Passive) - Test" for more information.
Result: There are no active or logged codes.
Proceed to Test Step 2.
2. Maintenance Schedule
A. Check the maintenance schedule for the engine.
Refer to Operation and Maintenance Manual, "Maintenance Interval Schedule"
B. If required, perform and ash service.
Maintenance Schedule
Result: Ash service is required.
Refer to Operation and Maintenance Manual, "Diesel Particulate Filter - Clean"
Result: Ash service is not required.
Proceed to Test Step 4.
3. Check the Engine Oil Level and Obtain an Oil Sample
A. Check the oil level and obtain an oil sample. If the oil level is high refer to Troubleshooting, Oil Contains Fuel if fuel is present.
Oil
Result: The engine oil sample shows moitor or action required, then skip to Test Step 5. Make necessary repairs.
Proceed to Test Step 4.
Result: The engine oil level is not at the correct level. Determine the root cause of why the oil level was high or low. Fill or remove the engine oil to the correct level.
4. Low Compression
A. Perform a compression test. Refer to Systems Operation, Testing and Adjusting, "Compression - Test"
Possible causes of low compression:
- Faulty piston
- Faulty piston rings
- Worn cylinder bores
- Worn valves
- Faulty cylinder head
- Damaged cylinder head
Compression
Result: Low compression is present.
Make the necessary repairs.
Result: Low compression is not present.
Proceed to Test Step 5.
5. Fuel Injectors
A. If service has been performed on the engine fuel system recently, verify that the injector trim codes in the Engine ECM match the injector for each cylinder. If injectors were moved between cylinders or if an injector was replaced and the injector trim codes were not updated in the Engine ECM, this can cause an engine miss.
B. Access the "Cylinder Cutout Test" in the "Diagnostic Tests" under the "Diagnostics" menu. Cut out each cylinder one at a time to listen for improvements in the engine. If engine sound improves while cutting out a specific cylinder or cylinders, then check that the injector(s) are working properly by using 440-6907 Injector Kit.
Note: The injector deliver quantity is not a reliable indicator of a failed injector. It is not recommended to use that test in determining if an injector is failed.
Fuel Injectors
Result: If injector(s) trim codes for each cylinder do not match what is in the Engine ECM, then refer to Special Instruction, REHS9707, for the procedure to install