WASHER (Plain) 8H3526 - Caterpillar

Use this procedure in order to troubleshoot a problem with high DEF pressure or use this procedure if the following event code is active. Refer to Troubleshooting, "Event Codes" for information about event codes. Note: The term Diesel Exhaust Fluid (DEF) and the word reagent are used interchangeably in some code descriptions and labels.
Table 1
Event Code
Code and Description Conditions which Generate this Code System Response
E930 (1)
High Aftertreatment #1 SCR Dosing Reagent Pressure The DEF pressure is above the trip point for the programmed delay time. The code is logged.
Dosing is disabled until the pressure is correct. Note: Use Cat ET to verify any suspected code. Determine what codes are present. Evaluate all codes for possible interaction. Refer toTroubleshooting, "Diagnostic Trouble Codes" and Troubleshooting, "Event Codes" for direction.Probable Causes
Supply air pressure is high
Dosing air assist pressure is high
DEF pressure sensor circuit problem
DEF return valve (pneumatic) is stuck closed
Frozen or obstructed line or injector nozzle for DEFRecommended Actions
Supply Air Pressure is High
Check the pressure gauge for the air supply to the dosing cabinetThe cabinet requires a regulated air pressure range of 724 to 1034 kPa (105 to 150 psi ), expressed here as gauge pressure.Dosing Air Assist Pressure is High
Note: Attempting to adjust the regulator will destroy the regulator. The only service option is to replace the regulator.There may be a problem with the air pressure regulator in the dosing cabinet.Monitor the status for "Aftertreatment #1 SCR Dosing Air Assist Absolute Pressure" on Cat ET. This pressure is after the pressure regulator and the air assist valve (solenoid). The air assist valve (solenoid) must be energized for air pressure to reach the air pressure sensor.Activate the "Aftertreatment #1 SCR Dosing Air Assist Valve Command Override" and record the pressure. The pressure must be in the range of 414 kPa to 469 kPa (60 to 68 psi), expressed here as gauge pressure. Replace the regulator if the pressure is out of range.DEF Pressure Sensor Circuit Problem
Note: A bad connection or a malfunctioning sensor may cause an in range failure, that will not trip a code for the sensor. If suspected refer to Troubleshooting, "Sensor Signal (Analog, Active) - Test" for direction.Inspect all connectors and wiring for the circuit.
Perform the wiggle test for all wires and connections in the circuit.Wiggle Test - The wiggle test allows the technician to monitor the status of the signals from the sensors. For additional information regarding the wiggle test, refer to the documentation that accompanies the Cat ET software.DEF Return Valve (pneumatic) is Stuck Closed
Activate the "Aftertreatment #1 SCR Dosing Air Assist Valve Command Override" to ON in order to open the air assist valve (solenoid).Activate the "Aftertreatment #1 SCR Catalyst Reagent Return Valve Override" to ON in order to close the DEF main tank return valve (solenoid).These actions should cause the DEF main tank return valve (pneumatic) to be open.The air returning through the DEF line will vent into the DEF main tank.Monitor the status for "Aftertreatment #1 SCR Dosing Reagent Absolute Pressure" on Cat