Does the dashboard temp gauge use the same sensor as the
DME
computer. My temp gauge sits on 100°, the lowest reading, and never moves yet I can see normal temperature operation while viewing “live data” via my diagnostic tool.
The dashboard gauge doesn't move from the "warm" position unless the car is still warming up, or badly overheating.
Typically the temp gauge will run right below or at 175 degree mark on the dash while running at normal operating temp. The only time I have seen a different reading from my dash to my scanner was when air was in the system after swapping a water pump or fluid change. Even vacuum filling it is tough to get the air out of the system.
Have you swapped coolant or a coolant component recently?
My understanding is that temp gauges in modern cars are not designed to accurately reflect the engine temp. They are more like three position idiot lights with a low, normal and high setting. Below is a thread where it is discussed in some detail.
I have a Benz that is old enough to have a temp gauge which varies with actual coolant temp. Since it’s my only car that shows any temp variation, it can be a little disconcerting even though I know that things are perfectly fine.
Water Temperature Accuracy
I've noticed in 105 degree traffic, the coolant temp per the gauge remains the same (about 177 degrees). I used to have a Mazdaspeed 6, along with a DashHawk (which would tap into about any parameter in the car's computer). In traffic, the coolant temp would get up to 225, displayed on the...
www.planet-9.com
You'd think that real sports cars would have real gauges. Pitiful. But the question remains - is there just one sensor that feeds the "gauge" and OBD2? I am taking water temp via OBD2 and
Cobb Accessport
and there seems to be little correlation once you get up to temp and beyond. If only one, does anyone know where it is?
I've seen the same thing with a scanner reading from the ODB port verses the dashboard gauge. I can't imagine how you could have any sensor that was so constant. I'd guess there's only one sensor and then a bit of computer logic ("illogic") that uses that data to compute a value to be shown on the dash. I've also noticed that the dashboard needle shows fully warmed up a little before the ODB port scan; i.e.: dashboard is a little ahead in temperature while the temperature is low. I have a
987.1
, so your mileage may varry.
Only one sensor. As PorscheGreg described, the computer uses the data to provide a three-position idiot light. The rumor is that
Porsche
got tired of addressing questions on temperature from owners, e.g. why does my temp rise when at a stop light. So they provide a 'smoothed' temp reading on what one would think is an analog gauge. On my
987.2
, about the only thing the gauge is useful for is to determine if the engine is up to temp. Monitor temps through OBDII and you'll see this is true.
