So I changed the temp sensor to the green top style, after having thrown numerous engine codes indicating this was the problem.

Immediately after the green top went in, the car would not warm up to "normal" operating temp for at least 30 minutes, maybe longer....made me think the thermostat was stuck open.

Last night, after a couple of weeks ofconsistently taking too long to warm up, I decided to put the black sensor back in and, lo and behold.....the car warms up to operating temp in a couple of miles and sticks there like a rock.

Ideas? Wrong or bad green top sensor...I got from ECS.

 

The part you changed is a temp sensor and its sole job is to read coolant temp. My guess is that its bad and your car was warming up all along and it was reading an incorrect temp. It has absolutely no control over the thermostat and your car warming up.

 

Agreed - the sensor senses....but it also reports tothe ECUand ECU's do make decisions.

However, ECU's don't operate thermostats any more than a sensor does, so I tend to agree that the green top is bad or maybe just the wrong one.But it does not make complete sense to me, unless this sensor is providing the temperture measurment being reported on on the dash?

 

Update:
Called Ecstuning and they are shipping another green top today. So I will install in a week or two (on vacation all next week, thankfully ), and let you all know the outcome.

 

What else would the sensor be doing? If the sensor didn't report to the ECU what would be the point of having the sensor? I think you answered your own question there

 

The question of whether this particular sensor is responsible for reporting the measurement at the dash is not answered by our mutually unnecessary rhetoric about what sensors do in life....though that part is at least fun, so I will add that not all sensors report tothe ECU - someapplications only drive a gauge, fuel level for example.

 

ahhh, but you can make changes to the level the fuel gauge reads thru the ECU.... now what? ; )

 

I suspect what you describe is simply artifically "adjusting" the gauge...not sensor calibration through the ECU (forward or backward).

Game on

 

I think see what you are saying.Do you mean the sensor itself is sending the readings to the gauge itself?? I would think that it would send it's info to the ECU and the ECU would inturn send the info to the dash.

If you use achttungs example about the fuel gauge (I have not done this myself with VAGcom) then that would tell me that the dash reading for the fuel gauge sensor is via the ECU. So the fuel gauge must be reporting to the ECU. You are right about some fuel gauges reporting directly to the dash....as in a boat for example.

 

Per Bently the ECT reports both to the ECM/ECU (pin 3) and temp gauge (pin 1). Pins 2 and 4 are grounds. YEAH! We all get a cookie for being part right.