Temp guage not working
It's most likely one of two things: 1) coolant temp sensor (meaning the gauge isn't working), or 2) stuck thermostat (meaning the gauge is working but the coolant isn't getting hot)
Start with the coolant temp sensor - it's on the back of the engine, somewhat near the top, toward the passenger side. On your car it's likely a blue sensor body (as is the CTS on my 99 A4 2.8). The easiest way to get to it is to remove the tube leading from the airbox to the throttle body. Take that off, and you can look down and see that there's a squarish plug with four wires plugged into the top of the coolant temp sensor (at the right angle you can see the color of the sensor - black, blue, or light green, but most likely blue on your car). There's a C-shaped retaining clip that holds the connector onto the sensor which must be pulled off (pull more or less straight back toward the firewall), and then the sensor can be unplugged. The sensor itself is just pressed into the opening in the block, not screwed in - you just have to pull upward to get it out (it can be tough - try opening the cap on the coolant tank to alleviate pressure in the system). The sensor is not expensive (around $25 from www.ecstuning.com - call them up with your VIN number to guarantee they send you the right sensor).
If you change that out, and it doesn't fix the problem, don't sweat it - it means your temp sensor was working, but replacing it was a good idea anyhow since they're prone to failure and can cause all kinds of wacky problems when they go. Next most likely problem is a thermostat stuck partially or fully open, and this is more invasive - it requires removing the front bumper, opening up the core support (with radiator and AC condensor), losing (and having to flush and refill) your coolant, and the removal of the serpentine belt and fans. It sounds horrifying but it's pretty easy actually.
I'd suggest starting with the CTS and see if it fixes the problem. If it does not, reply here and let me know and I can help you through the thermostat replacement if you're mechanically inclined and have the tools. If you're in the northeast, I can do either repair for you (I'm in the southern tier of NY) and save you a bundle over a dealership, and save you the aggravation of doing it yourself if you're not mechanical or don't have the tools or experience.
Apr 15, 2009 |
1998 Audi A4