minsicomm

This morning, when I started the Q7 (07, 4.2), it gave me the indicator in red for coolant and the MIL light in yellow.

I immediately turned the car off, and checked the coolant level, and based on what the owners manual says, its where it should be when cold. When I started it up again, the coolant warning was gone, but the MIL stayed on.

Now, last winter the MIL would go on intermittently, and my local VW dealer who handles anything I think needs VAG com said that they couldn't recreate that condition that turns it on at start up. It would often come on at start up, and then turn off at some point while driving. But there would be stretches where it wouldn't come on at all. They suggested that it only happens when it is starting in every cold temps, but my car is garage kept and it never gets below around 55 or 60 in there in the winter, so my morning starts, where the engine is dead cold, shouldn't have this happen, and when out an about, the engine should be sufficiently warm. Right? What I am saying is that I don't buy a guess of "the cold weather does it, we want to keep it over night" because 30 and 40 degree outside temps should cause any car to throw on a mysterious engine indicator.....right? Am I crazy?

They reset it every time I came in, just to be sure, but they were stumped. So, these visits were always gratis.

So....are these warning indicators related or not? What would cause the coolant warning to go if the coolant is at the appropriate level? What things fire off the MIL that seem to leave no code?

chingwodapigu

I've had an occasional low coolant warning on very cold nights...checked the level and it was fine. In my case, Techs think that it's probably the sensor in the overflow tank, and it's not really a concern because it goes away after the engine bay warms up, and it only happens once in a blue moon on really cold nights when I park outside.

minsicomm

So, then do I need to add a little coolant, or just let it be? This was a start in the garage, maybe at 55 degrees? Not super cold.

igotag

Not uncommon in colder weather. You could top it off a little bit if it annoys you, but as long as it goes away after warm up you should be fine.

chingwodapigu

If the coolant level is correct, I wouldn't worry about it.

chingwodapigu

As for the MIL, is that the check engine light you're referring to? If so, could it be your gas cap seal is starting to get old? Mine is starting to crack, and I have to make sure it's put on tight after a fill-up.

minsicomm

Ok, I'll take a look there. I assume that if its chronic, I can replace the gas cap fairly easily?

Anyway, to follow up, I checked on the coolant level from dead cold in my garage, not after a start, and it was low. I topped it off with the G-12 stuff.

I idled the car for 10 minutes in the driveway and could see or smell no evidence of a leak. I have had the car 2.5 years, its got almost 75k miles on it, and this is the first time his has happened. Should I be concerned, or is this just routine stuff, to have a small bit of loss over the long term for whatever reason?