CYLINDER AS 1U1765 - Caterpillar

Table 1
Diagnostic Trouble Codes    
J1939 Code    CDL Code    Code Description    Comments    
4334-16     E930 (2)     Aftertreatment 1 Diesel Exhaust Fluid Doser Absolute Pressure : High - moderate severity (2)     The DCU detects that the DEF pump pressure is above the acceptable range.
The code is logged.    
Follow the troubleshooting procedure in order to identify the root cause of the problem.    
Illustration 1 g03755376
(1) Backflow line connection at DEF Header (2) Backflow line connection at DEF PumpComplete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps    Values    Results    
1. Check the Backflow Line for a Restriction
A. Turn the keyswitch to the OFF position. Allow 2 minutes to elapse before proceeding.
B. Remove the backflow line from the DEF header and the DEF pump.
C. Inspect the backflow line for obstructions. Flush line with water/low pressure air if necessary.
Possible obstructions are ice, DEF deposits, or debris.
   
Restriction    
Result: An obstruction was found.
Repair: Flush the line or replace the line.
Proceed to Test Step 4.
Result: An obstruction was not found.
Proceed to Test Step 2.
   
2. Replace the Backflow Fitting
A. Replace the backflow fitting on the DEF pump. Refer to the Disassembly and Assembly manual for the correct procedure.
   
Replace Backflow Fitting    
Result: The fitting was replaced.
Proceed to Test Step 3.
   
3. Check for a Restriction in the DEF Pump
A. Reinstall the backflow line onto the DEF pump. Place the other end of the line into a bucket or beaker to collect the DEF.
B. Turn the keyswitch to the ON position. Do not start the engine.
C. Connect to the "Diesel Exhaust Fluid Controller #1 ECM" in Cat® ET.
D. Perform the "DEF Dosing System Verification Test". Refer to Troubleshooting, "Cat ET Service Features" for more information.
   
DEF Present    
Result: DEF did not flow from the DEF backflow line into the container.
Repair: Replace the DEF pump and reinstall all DEF lines. Refer to the Disassembly and Assembly manual for the correct procedure.
Proceed to Test Step 4.
Result: DEF flowed from the backflow line into the container.
Repair: Reinstall the backflow line onto the DEF header.
Proceed to Test Step 4.
   
4. Perform a "Aftertreatment System Functional Test "
A. Start the engine.
B. Connect to the "Engine #1 Aftertreatment Controller" in Cat ET.
C. Perform the "Aftertreatment System Functional Test ".
   
Diagnostic Code    
Result: The test was successful.
Return the unit to service.
Result: The test was not successful. There are additional codes.
Repair: Troubleshoot the additional codes. Refer to Troubleshooting for the correct procedure. Verify that the problem is resolved.