John Deere Error Code F14100 — What It Means and How to Fix It

Applies to: 6R Series (2013+), 7R Series (2013+), 8R Series (2013+), 9R Series (2013+)

JD F14100John DeereManually verified

DEF Level Sensor — Signal Out of Range

The diesel exhaust fluid (DEF) level sensor is reading outside its expected range. The SCR after-treatment system may be affected.

Repair difficulty

Experienced DIY

Repair time

1h

Dealer cost

$450-750

Likely causes

  1. 1

    Crystallised DEF fouling the sensorMost likely

    DEF crystallises on the sensor probe, especially if the tank has run dry or the fluid quality was poor. The DEF tank typically needs to be drained and flushed.

  2. 2

    Failed DEF level sensorPossible

    The sensor element degrades after prolonged DEF exposure. A new sensor is the fix if the tank is clean.

  3. 3

    Low or empty DEF tankPossible

    If the tank is genuinely low, refill with ISO 22241-compliant DEF first. Some machines throw this code before the level-low warning.

Parts needed

Tools needed

  • torx bit set
  • DEF-safe funnel
  • clean water for flush

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