My fans come on only when I shut it off, if the car is warm enough, not every time I shut it off, as it should I imagine.

But when running and the car is hot enough, as in traffic, they do not kick on.

The only way I can get them to turn on is to turn the key to the off position, fans go on, let it cool, then turn back on the resume driving through traffic.

Is there a sensor to be replaced?

I found this option... am I on the right track?

I plan to get a OBD too.
thanks in advance!

 

replace this part, its located on the lower left side of your radiator.

 

That's what I will do- thanks much!