Coolant Valve 16512 code

Scanned with vag. The code is coolant valve 16512 / n214

The symptoms are it takes a long time for the needle to get to 190 of ever depending how far we go. Is this a thermostat or coolant sensor? How do you change the thermostat?

Yes, not reaching temp is due to thermostat. The code could be the temp sensor not reading properly.
If you have vagcom check both temp sensors to see if they match.
Never hurts to install a new thermostat either, however, if the temp sensor is the issue it won't fix the code.

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I never, ever, do the thermostat without replacing the sensor. The sensors are cheap, easy to swap, and fail often enough that it is not worth the hassle of guessing.

But you can watch the coolant temp data in both the Engine and the Instruments to compare both sides of the sensor, as it is unlikely they both fail together (but are both part of the same sensor, so...).

Really couldn't ask for an easier thermostat than the ALH. Get a new neck and o-ring, lock it in place and put it in as an assembly. Easy peasy.

Do you need to drain the coolant or the thermostat?

In the time it takes to read this thread, you could have replaced the thermostat.

Yes, there will be coolant that gets spilled. The thermostat lives in the water cooling system. You can drain the coolant from the drain and get some out, but you'll still lose some more with the CTS and thermostat.

You'll lose less than a gallon (diluted) if you don't collect coolant from the radiator. You'd just bend up the hose you pull off the end of the thermostat flange when you pull that.

I just did one because I failed to replace the thermostat properly and it leaked. Replacing the thermostat with a new one and new o-ring cured my long to warm up times. A leak like mine works the same as a thermostat that is failing open. And doing the sensor if you care to will not lose any more coolant since it is already out of the block from the t-stat change.

Cheers,

PH