KIT-PISTON 5139564 - Caterpillar

Table 1
Diagnostic Trouble Codes for DEF Pressure Is Low
J1939 Code Description Notes
4334-18 Aftertreatment 1 Diesel Exhaust Fluid Doser Absolute Pressure : Low - moderate severity (2) The Electronic Control Module (ECM) detects that the Diesel Exhaust Fluid (DEF) pressure has dropped below 390 kPa (57 psi) and remains below 410 kPa (59 psi) for at least 40 seconds.
The warning lamp will flash. The engine will be derated.
4374-15 Aftertreatment #1 Diesel Exhaust Fluid Pump Motor Speed : High - least severe (1) The ECM detects that the duty cycle of the DEF pump required to maintain DEF pressure is too high.
The DEF system is not dosing.
The battery voltage is at least 10 V.
The warning lamp will flash. The engine will be derated.
4375-16 Aftertreatment #1 DEF Pump Drive Command : High - moderate severity (2) The ECM detects that the PWM duty cycle for the DEF pump control is greater than 86 percent.
The battery voltage is at least 10 V.
The warning lamp will come on.
Follow the troubleshooting procedure in order to identify the root cause of the problem.
Illustration 1 g03713516
View of the DEF pump module
(1) DEF backflow line connector
(2) DEF pressure line connector
(3) DEF suction line connector
Illustration 2 g03713528
View of the DEF tank and DEF tank header unit
(4) DEF backflow line connector
(5) DEF suction line connector Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Check the DEF Gauge
A. Turn the keyswitch to the ON position.
B. Check the current position of the DEF gauge.
C. Clean dirt and debris from around the tank filler cap before removing the cap. Add DEF to the DEF tank.
D. Check for a change in the gauge position.
E. If the gauge is in the full position, drain DEF from the tank and look for a change in the gauge position.
Gauge position
Result: The gauge did not move by adding or removing fluid to the tank.
Repair: Remove the DEF tank header and check for a stuck float.
If the float was not stuck, replace the DEF tank header. Return the unit to service.
If the float was stuck, repair the stuck float, if possible. If the float cannot be repaired, replace the DEF tank header. Return the unit to service.
Result: The gauge moved by adding or removing fluid to the tank.
Proceed to Test Step 2.
2. Check the DEF Suction and Backflow Line Connections
A. Check that the DEF suction and backflow lines are connected to the correct connectors.
Refer to Illustration 1 and Illustration 2.
DEF line connections
Result: The DEF lines have been installed to the incorrect connectors.
Repair: Connect the DEF lines to the correct connectors.
Refer to Illustration 1 and Illustration 2.
Result: The DEF lines are installed correctly.
Proceed to Test Step 3.
3. Inspect the DEF Lines for Leaks
A. Turn the keyswitch to the ON position. Do not start the engine.
B. Connect to the electronic service tool.
C. Perform the "DEF Dosing System Verification Test" to pressurize the system. Refer to Troubleshooting, "Service Tool Features" for more information.
D. Inspect all of the DEF lines for disconnected lines or leaks.
Leaks
Result: