My temperature gauge has started fluctuating from normal to one step hot while driving at highway speeds (and also at lower speeds around town). I want to check the temp sensor but I don't where it is. If it's not the sensor, does anyone know what the problem might be?

 

Go to this link and use parameter 51 to see your actual coolant temperature in degrees celsius. Should be 90 degrees. My temperature gauge has been all over the place for the last year, this indicates a gauge issue rather than cooing/overheating.

http://www.wak-tt.com/tt/climatecontcodes.htm

 

My mechanic checked the actual engine temp and it was normal. I put in a new green top temp sensor and the gauge still goes to one notch above normal. Does it need resetting, and if so, how?

 

I'd burp the cooling system first to be sure there's no air in it and that you have the proper amount of coolant in the car.

 

Today, I started the car and took off the cap on the overflow bottle. I let the gauge come up to the 'normal' temp mark. Then, the overflow bottle overflowed, so I put the cap back on. The temperature gauge immediately went to the next mark past 'normal'. What happened? Do I have too much coolant in the system? If that's not it, what else could it be?

 

I pulled up the codes on the climate control panel. If I read right, code 49 is the coolant temperature. On the highway, it fluctuated between 102 and 105 c. This was both with and without the a/c on. When I got in stop and go traffic, the temp actually went DOWN slightly. I checked the fans and they are both running. The only thing unusual that has happened lately is the my skidplate disappeared, wouldn't you know it, right after I had my oil changed. Guess they didn't put it back on correctly. By the way, code 51, which I believe is the oil temp, stayed at a steady 90 c.

 

One more thing I need to mention. When I slow down, the temperature drops, and while running at 60 mph, if I drop it into 5th gear (from 6th) the temperature also drops. Does this indicate a water pump problem, and can it be checked without taking the water pump out of the car? Could I be needing to flush the radiator?

 

The problem can prevail due to many reasons like Electrical Problems, Water Thermostat Failure, Cylinder Head Gasket Leaks, Coolant to Water Ratio, Low Coolant Levels. If coolant isn't flushed for once in 3 years you can expect this problem.

 

I'm now in the process of replacing the thermostat and flushing the system