You are correct, I don't know what would happen to the VW gauge alert
circuit if the subie sender gets too hot.

I used to replace the Subaru single wire sender with the VW one-wire
sender, but that involves re-tapping the hole in the coolant manifold
but then you would expect it to behave properly with the VW gauge.

After the initial bleeding, I've never had trouble with Subaru
engines overheating so I figured the Subaru sender is fine....and I
have a habit of checking the gauge while I drive anyway...

>The problem is that your approach only calibrates for normal temp.
>It does nothing to address the issue I expressed doubt about. The VW
>temp gauge has an over temp warning led circuit built into the gauge
>to get the driver's attention when the temp is too high. How does
>your resistor affect the point at which this warning is triggered?