As the preheater upgrade kit contains components about in 20...70EUR value, I didn't want to pay 300+ EUR for Eber or Webasto upgrade kit. So I bought 2 relays, 3 fuse holders, cables and connectors for less than 20EUR. And I'm planning to build a timer controller with bluetooth connection and Android app. But you can also buy a simple 12V 7days timer and a delay timer relay for coolant pump from eBay with 10...20EUR (coolant pump should run a minute after stopping the aux heater). So if you have skills in electric work or electronics, you can upgrade your aux heater with less than 40EUR :) I also made a little overview manual of my upgrading process: http://ims.ut.ee/~teet/preheater/preheather-manual.pdf And also shorcuts to Eber and Webasto manuals: http://ims.ut.ee/~teet/preheater/eber-manual-de-en.pdf http://ims.ut.ee/~teet/preheater/webasto%20manual.pdf