SEGMENT (std.) 5S0724 - Caterpillar

Use this procedure to troubleshoot a low dosing air assist pressure. Also, use this procedure if one of the following event codes is active or logged.
Table 1
J1939 Code and Description CDL Code and Description Comments
4335-17
Aftertreatment #1 SCR Dosing Air Assist Absolute Pressure : Low - least severe (1) E964 (1)
Low Aftertreatment #1 SCR Dosing Atomization Air Assist Pressure The air pressure is below the trip point for the programmed delay time.
Dosing is disabled until the pressure is correct.
The code is logged.
4335-18
Aftertreatment #1 SCR Dosing Air Assist Absolute Pressure : Low - moderate severity (2) E964 (2)
Low Aftertreatment #1 SCR Dosing Atomization Air Assist Pressure The air pressure is below the trip point for the programmed delay time.
Dosing is disabled until the pressure is correct.
The code is logged.
Table 2
Associated Codes
J1939 Code CDL Code Troubleshooting Procedure
4335-3 3092-3 Troubleshooting, "Sensor Signal (Analog, Active) - Test"
4335-4 3092-4 Troubleshooting, "Sensor Signal (Analog, Active) - Test"
4336-5 3094-5 Troubleshooting, "Solenoid Valve - Test"
4336-6 3094-6 Troubleshooting, "Solenoid Valve - Test" Probable Causes
Codes
Leaks
Air pressure
SensorRecommended Actions
Table 3
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Turn the DC breaker to the ON position.
B. Connect Cat® Electronic Technician (ET) to the service tool connector.
C. Look for active codes that are associated with the system for the event code.
Codes
Result: An associated code is active.
Repair: Troubleshoot any associated codes before continuing with this test.
Result: A code is active or logged.
Proceed to Test Step 2.
2. Check for Air Leaks
A. Turn the DC breaker to the OFF position.
B. Inspect the air supply lines to the dosing cabinet and inside the dosing cabinet for leaks.
Leaks
Result: An air leak was found.
Repair: Repair the air leak.
Proceed to Test Step 5.
Result: An air leak was not found.
Proceed to Test Step 3.
3. Check the Air Supply to the Dosing Cabinet
A. Turn the DC breaker to the OFF position.
B. Disconnect the air supply line to the dosing cabinet.
C. Install a pressure gauge on the air supply line to the dosing cabinet.
D. Monitor the air supply pressure from the air compressor.
E. Reconnect the air supply line to the dosing cabinet.
483 kPa to 1068 kPa (70 psi to 155 psi)
Result: The air supply pressure from the air compressor is 483 kPa to 1068 kPa (70 psi to 155 psi).
Proceed to Test Step 4.
Result: The air supply pressure from the air compressor is less than 483 kPa (70 psi).
Repair: There is a problem with the air supply to the dosing cabinet. For information on the air compressor, refer to the Original Equipment Manufacturers (OEM) service information.
Proceed to Test Step 6.
4. Check the Aftertreatment #1 Supply Air Pressure Sensor
A. Turn the DC breaker to the ON position.
B. Connect Cat ET.
C. Use Cat ET to monitor the following pressures:
- "Aftertreatment #1 Supply Air Pressure"
- "Aftertreatment #1 DEF Dosing Pressure"
Sensor
Result: The pressure sensors are within 20 kPa (3 psi) of each other.
Proceed to Test Step 5.
Result: The pressure sensors are not within 20 kPa (3 psi) of each other.
Repair: Replace the "Aftertreatment #1 Supply Air Pressure" sensor.
Proceed to Test Step 6.
5. Check the Air Assist