DEF Tank Level Sensor Malfunction

What this code means

The DEF tank level sensor is reporting incorrect or no reading.

Symptoms

• DEF level gauge inaccurate
• False low DEF warning
• Cannot determine DEF level
• Potential unnecessary derate warning
• Service message for DEF

Common causes

• Level sensor float stuck
• Sensor wiring corrosion
• Crystallized DEF on sensor
• Tank sender unit failure
• Short circuit in sensor

Diagnostic steps

1. Read DEF level PID and compare to actual
2. Inspect DEF tank sender unit
3. Check sensor wiring for corrosion
4. Test sensor resistance range
5. Add known quantity of DEF and check reading

Repair notes

Replace DEF tank level sender unit. Clean DEF tank if crystallization is present.

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