In my experience the diesel fluid destroyes the DEF heater ribbons(tank heater) and also had to replace the DEF lines(these lines are also heated). This applies to GM cars and trucks, but, can't see tractors having that much different components.
Here is the publication from Kubota,
DEF Tank Contamination with Diesel Fuel; SVL95-2S, M5, M6, M7
Document ID GE236
Status Published
Published Date 12/18/2019
Title
DEF Tank Contamination with Diesel Fuel; SVL95-2S, M5, M6, M7
Issue
Issue:
The customer filled up the DEF tank with diesel fuel and continued to operate the machine. The following codes can become active if operated long enough:
E: 9520 (Diesel Exhaust Fluid Quality Error)
E: 9601 (Engine Output Limit)
E: 9602 (Engine Idling Limit)
Diagmaster may show DTC: P207F (Diesel in DEF Tank)
Note: The DEF defrost lamp has been reported with diesel fuel contamination. If the customer says the DEF defrost lamp is turned on, make sure the DEF tank is not contaminated with diesel fuel.
Solution
Solution:
Due to contamination and degradation from diesel fuel, the following components will need to be replaced:
- DEF Header, Assembly
- DEF Injector
- DEF Fluid Pump
- SCR Selective Catalyst Reduction Muffler Assembly
- DEF Injection Lines
The DEF tank will need to be flushed and cleaned with deionized water. The DEF "Injection Compensation (ACU)" will need to be performed through Diagmaster for the new DEF injector.