What is SPN 3360 FMI 10 & How to Solve It?

What is SPN 3360 FMI 10:

SPN 3360 relates to the DEF Tank Level Sensor, and FMI 10 means the sensor is showing abnormal behavior, though still partially functional.

This code usually appears when the DEF level readings are inconsistent or not matching actual tank content, causing confusion in dosing and possibly triggering derates.

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Why This Happens

• The DEF level sensor is degraded or coated in crystals.
• Electrical interference in the sensor signal.
• Wiring harness or ground issue.
• DEF tank float stuck or sensor resistor band damaged.

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How to Fix It

1. Drain and clean the DEF tank and sensor.
2. Test the level sensor signal while refilling the tank.
3. Check wiring and connectors for corrosion or low voltage.
4. Replace the sensor if level readings remain inconsistent.
5. Clear the fault and monitor real-time DEF level reporting.

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How to Avoid It Before It Happens

1. Use only sealed and filtered DEF.
2. Rinse tank and level sensor annually or every 2,000 hours.
3. Replace the sensor if you notice frequent dosing interruptions.
4. Avoid leaving tanks half full in freezing temperatures.

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