I am using the diagnostic codes to see what my coolant temps are at.

http://www.audiworld.com/tech/int5.shtml

From looking at the chart 51 is for the coolant temp but I never go above 90c / I think is around 194f. I have let the car sit and idle until my fan comes on but it still reads 90. Does anyone know if 51 is the right code for the coolant temp? Is 90 the max it will go? I noticed RPM is 28 but on my car its actually 27. Was wondering if there were any other known differences or if someone can verify that 90 is the max. I have 99 1.8. Thanks

 

194 is right on target considering that is right around the temp of the thermostat. During the summer you may get higher temperatures though as the cooling system isn't able to keep up as efficiently.

 

But my display will not go above 90. Now that I think about it the display is always on 90 when the car is warmed up, it never goes up or down. I thought the fan turned on around 200f which should display somewhere in the low 90's, around 93 I think. So I assume 90 is the max the display will go? Is there another way of checking actual temp?

 

Perfect, is it lower when the car is cold? If so, all is well in the world.

The temp that the fan goes on is dependent on which temperature switch you have on the fan, and whether you have the air conditioning running.

 

That seems to be the problem. It never changes after the car warms up, always on 90. Which is why I was wondering if 51 was actually the correct block, maybe I am reading something else. I would think it should go up when the car warms up (sitting and idling) and come back down when the fan turns on to cool things off again. It never changes from 90.

 

The instrument cluster coolant guage isn't very reliable. And in fact it's not suppose to be. It is designed to park itself at 90 as soon as the thermostat pops open. If the thing was fluctuating all the time people would freak out and think something was wrong. It should always be right around 90 and not move unless it is hot as hell and you have the AC on.

 

I hope im not beatin a dead horse here but I was concerned with the display on the climate control panel. I would think that would be more accurate and move up and down with temperature change. Or is that one as reliable as the dash gauge?

 

I would think the thermostat would keep the temperature right where it should be at a constant temperature.