Overheating in freezing weather?!

[muleof1999]

I live in Central Pennsylvania, and when I got up for work at 4am, I went out to start my car. It was 7 degrees fahrenheit (-15 degrees celsius). The second my car fired up, the temperature warning light started flashing and beeping. I let it go for a few seconds thinking that the thermostat may have frozen or something, but it never stopped flashing. I know it's impossible that it was overheating, even if just for the fact that it was running for a total of 20 seconds. But, I am baffled as to what the problem could be, and if it's really safe to drive it or not? I've NEVER had this problem, or even seen this warning light come on before. I'm very alert/aware of any problems with my car and take care of them right away.

1999 Audi A4 Quattro - 123,000 miles - very well maintained

Any help anyone could provide would be greatly appreciated!

[Dave Avant]

Maybe the very cold weather has confused the sensor. It might need replacing, so long as all the coolant pipes warm as they should then it should be fine.

[RickT]

yeah the cold could of got to the sensor...

i would see what happens later today, where abouts do the temp gauge read??

Cheers

RicKT

[muleof1999]

The actual temperature gauge reads through the floor. It's BELOW the lowest measurement. Again, I only ran it for 20 seconds or so, because the beeping and the light were making me afraid I was going to break something. I'll try to start it again later today...when it gets "warmer". Let you know what happens...

If it is the sensor, what do you think the odds are that it may have been permanently damaged?

[Dave Avant]

Normally those type of sensors as they are basically a resistor, when they go 'funny' they normally need replacing.

As the guage, well on my 03 A4 starts at 50 degrees, if its well into minus figures it may well read lower than the first mark, I've seen this in other cars when its very cold or even comparing between summer/winter the guage will sit in a lower position when cold. It might sit on the lowest line and when the ignition is turned on, it will drop a bit.

I'd start it, feel the coolant pipes and check the expansion tank to make sure the coolant isn't frozen. The main top/bottom hose to the rad won't get warm initially.

[muleof1999]

Thanks everyone. Got it fixed. When I started it yesterday afternoon. The thermostat light didn't come on right away. I never checked to see if the resevoir was frozen, cuz I didn't feel like taking the plastic covers off the engine in 12 degree weather. Also, after you started talking about it freezing, I realized it's definitely probably time to replace the anti-freeze. Went and had a flush and fill, and now it runs like a dream, all over again! Thanks for the suggestions, they helped me realize the problem!

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