John Deere 4345.06 – ECU: DEF Dosing Unit Return Line Heater Circuit Has Low Resistance
Issue description
The ECU has detected that the circuit resistance is too low, which specifically indicates a short circuit to ground. This malfunction can prevent the heater from functioning properly, which is critical for preventing Diesel Exhaust Fluid (DEF) from freezing in the lines during cold conditions.
Applies to these machines
40 machines- 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
- 8245R to 8400R
- 6105M
- 6100D
- 6110D
- 6115D
- 6125D
- 6130D
- 6140D
- 210G
- 210GLC
- 544K-II
- 4045 PowerTech
- 4.5L diesel engines
Check the cause
Inspect Wiring and Connections: Check for any damaged, frayed, or loose wiring and connectors in the DEF dosing unit line heater circuit.
Check for Short Circuits: Because the ".06" failure mode specifically denotes low resistance, carefully inspect the circuit for points where wires may be rubbing or touching the chassis/ground, causing a short circuit.
Test the Heater Element: Use diagnostic tools or a multimeter to test the heater element for proper resistance.
Verify Electrical Supply: Ensure that the electrical supply to the heater is stable and within specifications.
Repair steps
Locate components
Locate the DEF Dosing Unit Return/Supply Line Heater and its associated wiring harness.
Repair wiring
Repair or insulate any sections of the wiring harness that are shorting to ground.
Repair connectors
Repair or replace any damaged or corroded electrical connectors.
Replace heater
If the wiring is intact but the heater element itself fails the resistance test (internal short), replace the faulty DEF line heater.
Reset ECU
Once repairs are complete, reset the ECU to clear the fault code.
Monitor system
Monitor the system to ensure normal operation and verify that the fault code does not return.
Parts you might need
(2)DEF Dosing Unit Supply Line Heater
Internal schematic identifier E5602
DEF Dosing Unit Return Line Heater
Internal schematic identifier E5603
Get help to fix this fault by requesting a quote
