Description:

This diagnostic code indicates that the DEF dosing unit has failed to relieve system pressure during a shut-off sequence or a new suction sequence. This condition can cause improper DEF dosing and affect the performance of the aftertreatment system.

Reaction:

The ECU may limit or modify DEF system operation to prevent potential damage, potentially impacting vehicle performance and emissions control.

Recommendations:

• Inspect DEF Dosing Unit: Check the DEF dosing unit for any blockages or malfunctions that could prevent pressure relief. Clean or replace components as necessary.
• Test Pressure Relief Mechanism: Ensure that the pressure relief mechanism in the DEF dosing unit is functioning correctly.
• Check for Contaminants: Inspect the DEF for any contaminants that could be causing pressure issues and clean the system if needed.
• Verify Pressure Sensors: Use diagnostic tools to check the pressure sensors and ensure they are providing accurate readings. Replace faulty sensors if necessary.
• Reset ECU and Monitor System: After addressing the pressure relief issue, reset the ECU to clear the fault code and monitor the system to ensure normal operation.

Note:

Proper pressure management in the DEF dosing unit is critical for effective DEF injection and maintaining the efficiency of the aftertreatment system. Regular inspections and timely maintenance can help prevent pressure-related faults.