John Deere 4341.06 – ECU: DEF Dosing Unit Pressure Line Heater, Resistance Too Low

The ECU has detected that the electrical resistance in the DEF dosing unit pressure line heater circuit is too low, typically indicating a short to ground. This can prevent the DEF from thawing in cold conditions, impacting DEF injection and emissions control. The ECU will often limit DEF system operation or derate the engine to prevent damage.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5090M
• 5100M
• 5100MH
• 5100ML
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 9470RT
• 9520RT
• 9570RT
• 6105M
• 5075GV
• 5090GV
• 5075GN
• 5090GN
• 5100GN
• 5075GL
• 331G
• 210G
• 210GLC
• Vermeer D24x40 S3
• Vermeer D40x55 S3

1. 1

   Visually inspect the DEF dosing unit pressure line heater circuit for any damaged, frayed, or loose wiring and connectors.

2. 2

   Inspect the circuit specifically for any points where wires may have rubbed through their insulation and are touching the chassis/ground, causing a short circuit.

3. 3

   Use a multimeter or diagnostic tool to test the heater element for proper resistance.

4. 4

   Ensure that the electrical supply to the heater is stable and within OEM specifications.

1. 1

   Isolate the short

   If the wiring inspection reveals a short to ground, repair or insulate the affected wires and secure the harness away from sharp edges or high-heat areas.

2. 2

   Replace the heater

   If the wiring is intact but the heater element itself fails the resistance test (internal short), remove and replace the DEF dosing unit pressure line heater.

3. 3

   Clear codes

   Reconnect all components and turn the key to the ON position. Use a diagnostic scanner to reset the ECU and clear the fault code.

4. 4

   Verify repair

   Run the machine and monitor the DEF system to ensure the heater operates correctly and the code does not return.