John Deere 5745.18 – ECU: DEF Dosing Unit Heater, Temperature Moderately Low

Issue description

The DEF (Diesel Exhaust Fluid) dosing unit heater outlet temperature is moderately lower than the expected operating range.

Inspect the DEF Dosing Unit Heater and surrounding components for any obvious signs of physical damage, corrosion, or wear.
Check the electrical supply and wiring harness to the DEF dosing unit heater to ensure they are stable, within specifications, and free of shorts or high resistance.
Test the DEF dosing unit heater for proper operation and verify the duration of its heating cycles using a diagnostic tool such as John Deere Service ADVISOR.
Verify that the timer settings for the DEF dosing unit heater are correct and functioning as intended by the ECU.
Review environmental factors, as extreme cold weather can sometimes contribute to faulty heater on-time readings or moderately low temperature outputs.

Perform diagnostic checks
Perform the diagnostic checks above to isolate whether the issue is environmental, electrical, or a hard failure of the heater element.
Replace the DEF Dosing Unit Heater
If the diagnostic tests confirm the heater is not functioning correctly and the wiring is intact, replace the DEF Dosing Unit Heater (or the integrated DEF Dosing Unit Pump, depending on the specific engine's parts breakdown).
Reset the ECU
Once the replacement is installed or the electrical fault is repaired, reset the ECU using a diagnostic tool to clear the 005745.18 fault code.
Monitor the system
Run the machine and monitor the system to ensure normal operation and verify that the code does not return during a DEF dosing cycle.

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DEF Dosing Unit Heater
Often integrated into or serviced alongside the DEF Dosing Unit Pump

DEF Dosing Unit Pump 2.2 Evo NRV
DZ111284
Interchanges with RE553796, DZ119472, DZ121771
DZ111284

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