I replaced the temp sensor on the radiator because the level was never going above one bar on the pod. I can now run the vehicle all over, to the point where the coolant spills out of the overflow container. And the fans will not kick on, nor will the temp gauge go above one bar. What else can I look at to try and diagnose the issue?

The device on the radiator is a thermo-switch, not a temp sending unit.

The temp sending unit is on the engine block and has a three wire plug.

I replaced the temp sensor on the radiator because the level was never going above one bar on the pod. I can now run the vehicle all over, to the point where the coolant spills out of the overflow container. And the fans will not kick on, nor will the temp gauge go above one bar. What else can I look at to try and diagnose the issue?

Check out the link on my temperature gauge issues, finally realized the sending unit lost ground. Your fan not working sounds like thermo sensor on the passenger side of radiator. I wired a manual switch on mine in case it failed again on the trails.
http://cfmoto-forum.com/z5550/z500-temperature-gauge/

I replaced the temp sensor on the radiator because the level was never going above one bar on the pod. I can now run the vehicle all over, to the point where the coolant spills out of the overflow container. And the fans will not kick on, nor will the temp gauge go above one bar. What else can I look at to try and diagnose the issue?

Check out the link on my temperature gauge issues, finally realized the sending unit lost ground. Your fan not working sounds like thermo sensor on the passenger side of radiator. I wired a manual switch on mine in case it failed again on the trails.
http://cfmoto-forum.com/z5550/z500-temperature-gauge/

Thanks for the input, and my apologies with the incorrect terminology.  The Thermo switch is what was replaced but no change.  Ironically, the post you referenced is what I was using to try and diagnose the issue further, but looking at it on my phone was troublesome. 

I also looked at the post referencing the installation of a switch on the thermo sensor.  However, I'm a little confused.  Is there a reason why you would want to switch the thermo sensor itself and not just a switch on the fans?  I haven't looked at the wiring diagram, but would it be problematic if I a switched 12v to the fan itself? 

I'll take a look at the grounding issue from the sending unit to see if that is the cause.  I'm just getting really frustrated because it is just one issue after another with this sxs.

[2015 Z Force 800 53/Trail EPS]

What year is this ZForce 500? The thermoswitch ..AKA fan switch only provides a ground for the fan relay coil when closed causing the relay to also close and provide power to the fan motor. A switch between the two leads just bypasses the function of the thermoswitch and manually provides that ground for the relay coil.

What year is this ZForce 500?

2017.  And thank you very much for the input!  It makes a lot more sense now why to use the thermoswitch.

[2015 Z Force 800 53/Trail EPS]

What year is this ZForce 500?

2017.  And thank you very much for the input!  It makes a lot more sense now why to use the thermoswitch.

2017 they were still using the thermoswitches. They only provided a ground for the fan relay but...they didn't work if the sensor end was not making contact with the coolant. The radiator must be filled to the very top with no air gaps between the coolant level and the cap. Also keep in mind that many ..thousands..of thermoswitches were defective or failed quickly. Also the relays were the lowest Chinese quality and like many other electrical components, couldn't handle the riggers of Western off-roading. This includes the fan motors themselves as they were stabbed into the mud and under water far more then they expected. So check that fan fuse as it may also have a problem.