Normal operation is 0.5-0.6V, 0.4V can be good too, but the 0.2 and 0.17V values means that your sensor measures a great heat. Since you put the engine in an AW11 (SW11 for now
) with a quite small engine bay (I still don't understand how did you manage to fit it
) it's possible that the engine becomes this much overheated when you turn it off, so your sensor migth be working well :S