JoeIndy35

I posted this in the 4.2 L thread but it's hard to get help there. I've got a 2007 Q7 4.2L.
So my expansion tank blew up 2 weeks ago. Ordered a new one, installed it, filled with proper coolant. Let it run, it got to temp, re checked the level, it was topped off perfect. Heater works perfect. Now I have a new issue. When I'm driving it, around 15 min after it gets to proper temp, the coolant warning light comes on. Temp gauge reads perfect, pull cap off, level is still perfect. What could be going wrong? Do I maybe need to bleed the system? Maybe air in it? What's odd is I can shut it off, start it back and no light. However 15 min later it will come back on. Possible bad level sensor in the new tank?

JoeIndy35

Oh, I'm using my older factory cap still. Not sure if that would cause an issue. No coolant leaks from it when it's running so assuming its fine

Edd W

Is the level sensor moulded into the tank or is it a separate unit?