Description:

This diagnostic code indicates that the resistance in the DEF dosing unit reversing valve circuit is too low, typically pointing to a short to ground. This condition can prevent the reversing valve from functioning properly, affecting the DEF dosing process.

Reaction:

The ECU may limit or adjust the operation of the DEF system to manage the low circuit resistance, potentially impacting DEF injection and overall emissions control efficiency.

Recommendations:

• Inspect Wiring and Connections: Check for damaged, frayed, or loose wiring and connectors in the DEF dosing unit reversing valve circuit. Repair or replace as necessary.
• Test Valve Element: Use diagnostic tools to test the reversing valve element for proper resistance. Replace the valve if it is faulty.
• Check for Short Circuits: Inspect the circuit for any points where wires may be touching ground, causing a short circuit. Repair or insulate as needed.
• Verify Electrical Supply: Ensure that the electrical supply to the valve is stable and within specifications.
• Reset ECU and Monitor System: After resolving the issue, reset the ECU to clear the fault code and monitor the system to ensure the valve operates correctly.

Note:

Ensuring the proper electrical function of the DEF dosing unit reversing valve is essential for effective DEF injection and maintaining the efficiency of the aftertreatment system. Regular maintenance and timely repairs can help avoid resistance-related problems.