TUBE 1321114 - Caterpillar

Table 1
Diagnostic Trouble Codes for the DEF Pump Pressure Sensor
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
4334-3 3090-3 Aftertreatment #1 SCR Dosing Reagent Absolute Pressure : Voltage Above Normal There is excessive voltage on the signal wire between the Diesel Exhaust Fluid Controller (DCU) and the DEF pump.
or
There is an open circuit on the supply, signal, or return wire.
The code is logged.
4334-4 3090-4 Aftertreatment #1 SCR Dosing Reagent Absolute Pressure : Voltage Below Normal There is low voltage on the signal wire between the DCU and the DEF pump pressure sensor.
The code is logged.
4334–20 3090–20 Aftertreatment #1 DEF #1 Pressure (absolute) : Data Drifted High The signal from the DEF pump pressure sensor is above 10 kPa (1.5 psi) when the DEF system is not primed.
4334–21 3090–21 Aftertreatment #1 DEF #1 Pressure (absolute) : Data Drifted Low The signal from the DEF pump pressure sensor is below −10 kPa (−1.5 psi) when the DEF system is not primed.
Follow the troubleshooting procedure to identify the root cause of the problem. Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Check that the Latest Available Software is Installed
A. Ensure that the latest software is installed on the engine ECM.
B. Ensure that the latest software is installed on the Dosing Control Unit (DCU)
If necessary, refer to Troubleshooting, "ECM Software - Install" for the correct procedure.
Software
Result: The latest software is not installed.
Repair: Install the latest engine ECM software and then install the latest DCU software. If necessary, refer to Troubleshooting, "ECM Software - Install" for the correct procedure.
Start the engine and wait for 2 minutes.
If the fault is cleared, return the engine to service.
If the fault is still present, proceed to Test Step 2.
Result: The latest software is installed.
Proceed to Test Step 2.
2. Check for Active Diagnostic Codes
A. Connect to the electronic service tool. If necessary, refer to Troubleshooting, Electronic Service Tools.
B. Check for active diagnostic codes.
Diagnostic codes
Result: A -3 or -4 diagnostic code is active.
Proceed to Test Step 4.
Result: A -20 or -21 diagnostic code is active.
Proceed to Test Step 3.
3. Check the DEF Pressure
A. Connect to the electronic service tool. If necessary, refer to Troubleshooting, Electronic Service Tools.
B. Turn the keyswitch to the ON position. Do not start the engine.
C. Use the electronic service tool to check the "DEF Pressure" parameter. −10 kPa (−1.5 psi) to 10 kPa (1.5 psi)
Result: The DEF pressure is between −10 kPa (−1.5 psi) and 10 kPa (1.5 psi).
Repair: Start the engine and allow the DEF system to prime.
Stop the engine and wait for the wait-to disconnect lamp to switch off.
Turn the keyswitch to the ON position. Check for an active 4334–20 or 4334–21 diagnostic code.
If the diagnostic code is no longer active, return the engine to service.
If the diagnostic code is still active, proceed to Test Step 4.
4. Replace the Pump and Electronics Unit (PEU)
Note: The PEU is a non-serviceable unit. If a fault is suspected in the PEU, the unit must be