DEF Pressure Is High
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C3.4B Engines
[UENR4499]
AIR INLET AND EXHAUST SYSTEM
AFTERTREATMENT GP
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| Diagnostic Trouble Codes for DEF Pressure Is High | ||
|---|---|---|
| J1939 Code | Description | Notes |
| 4334-0 | Aftertreatment 1 Diesel Exhaust Fluid Doser Absolute Pressure : High - most severe (3) | The ECM detects that the DEF pressure is greater than The battery voltage is at least 10 V. The warning lamp will flash and the engine will be derated. DEF injection is disabled when this diagnostic code is active. The diagnostic code will clear when the DEF pressure drops below |
| 4334-16 | Aftertreatment 1 Diesel Exhaust Fluid Doser Absolute Pressure : High - moderate severity (2) | The ECM detects that the DEF pressure has risen above The battery voltage is at least 10 V. The warning lamp will flash and the engine will be derated. When this diagnostic code becomes active, the DEF pressure will be reduced and the pressure build-up process will begin again . The diagnostic code will clear if the DEF pressure remains below |
| 4374-18 | Aftertreatment #1 Diesel Exhaust Fluid Pump Motor Speed : Low - moderate severity (2) | The ECM detects that the PWM duty cycle for the DEF pump speed is less than 4 percent.
The battery voltage is at least 10 V. The warning lamp will come on. |
| 4375-18 | Aftertreatment #1 DEF Pump Drive Command : Low - moderate severity (2) | The ECM detects that the PWM duty cycle for the DEF pump control is less than 4 percent.
The battery voltage is at least 10 V. The warning lamp will come on. |
| Follow the troubleshooting procedure to identify the root cause of the fault. | ||
Complete the procedure in the order in which the steps are listed.
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| Illustration 1 | g03712848 |
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View of the DEF pump module. (1) DEF backflow line connector | |
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| Illustration 2 | g03712856 |
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View of the DEF tank and DEF tank header unit (1) DEF backflow line connector | |
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| Troubleshooting Test Steps | Values | Results |
|---|---|---|
1. Check the Backflow Line for a Restriction A. Turn the keyswitch to the OFF position for 2 minutes. B. Remove the backflow line from DEF tank header (2) and DEF pump (1). C. Inspect the backflow line for obstructions. Note: Possible obstructions are ice, DEF deposits, or debris. |
DEF return line restriction |
Result: An obstruction was found. Repair: Flush line with water/low pressure air. If necessary, replace the line. Proceed to Test Step 3. Result: An obstruction was not found. Proceed to Test Step 2. |
2. Check for Leaks in the Pressure Line and for Restriction in the DEF Pump A. Connect the backflow line to DEF pump (2). Place the other end of the line into a suitable container to collect the DEF. B. Remove the DEF injector from the SCR canister. Leave the coolant and DEF lines connected to the injector. C. Turn the keyswitch to the ON position. Do not start the engine. D. Connect to the electronic service tool. E. Perform the "DEF Dosing System Verification Test". Wait for the test to complete. F. Visually inspect the DEF pressure line and the DEF injector for leaks. |
DEF pump restriction |
Result: The DEF pressure line is leaking. Repair: Replace the DEF pressure line. Result: The DEF Injector is leaking. Repair: Install a replacement DEF injector. Refer to Disassembly and Assembly for the correct procedure. Result: DEF did not flow from the DEF backflow line into the container. Repair: Replace the DEF pump. Refer to the Disassembly and Assembly manual for the correct procedure. Result: DEF flowed from the backflow line into the container. There are no visible leaks. Connect the backflow line to DEF tank header (1). If the fault is still present, contact the Dealer Solutions Network (DSN). |
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2014/10/20
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