Prosport Water Temps Gauge Reading Cooler

[alice]

I have had a prosport water temp gauge in my car for some time now and figured I would finally ask why it reads lower than my ECU. Basically, the Prosport gauge reads about 20* lower than the ECU. Now, could this be because of where I have the sensor? On my 2g, I have the Prosport sensor in the upper water neck that the upper radiator hose attaches to. All of the other ECU coolant gauge stuff is in the lower water neck.

So, is it possible that there really is a 20* difference between the upper and lower sensor locations? Or is the fact that I am grounding the Prosport sensor directly to the engine having something to do with the difference?

 

[RoryBarron]

It actually is possible since there should be a thermostat between the two. I can't really be any more technical than that.

 

[mike96]

I have had a prosport water temp gauge in my car for some time now and figured I would finally ask why it reads lower than my ECU. Basically, the Prosport gauge reads about 20* lower than the ECU. Now, could this be because of where I have the sensor? On my 2g, I have the Prosport sensor in the upper water neck that the upper radiator hose attaches to. All of the other ECU coolant gauge stuff is in the lower water neck.

So, is it possible that there really is a 20* difference between the upper and lower sensor locations? Or is the fact that I am grounding the Prosport sensor directly to the engine having something to do with the difference?

It depends on if the temp sensor is in the flow of cooled coolant coming into the engine as opposed to hot coolant coming from the engine. If I am not mistaken the upper hose is the cool into the engine and the lower hose is hot to the radiator. So the answer would be yes it is entirely possible...

 

[TuRBoTaLooN]

Just to add to this....

I had the same gauge and a similar issue at one point and called ProSport. Make sure you have the latest coolant temp sensor. They said the old style one (thats still being sold in some places) can read incorrectly by a margin of up to like 30 or 40 degrees. But yes, depending on where the sensor is, it can be off.