What is SPN 4376 & How to Solve It?

What is SPN 4376:

SPN 4376 relates to the DEF Dosing System, typically indicating a general dosing malfunction when no FMI is provided.

This means DEF dosing may be interrupted, inaccurate, or below demand.

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Why This Happens

• DEF pump or injector not functioning properly.
• Clogged dosing valve or frozen lines.
• DEF pressure sensor reading outside target range.

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How to Fix It

1. Inspect DEF system components for pressure, flow, and injection events.
2. Clean or replace dosing valve.
3. Warm system and test dosing command via diagnostics.
4. Clear the code and verify full dosing cycle.

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How to Avoid It Before It Happens

1. Monitor DEF usage and dosing cycle duration.
2. Replace clogged filters regularly.
3. Test injector and flow rates during PM.