I put a auto zone temp sensor in and the fans do not run, unless you unplug the sensor. What I need to know is the resistance readings I should get when checking it at different temps, hot/cold. That way I can tell if it's the aftermarket sensor that is the problem. Thanks.  I am getting 220ohms at 212 F and 2.4k ohms at 40 F.    Seeks like that should be in the neighborhood from readings off other thermistors ive checked.

Edited January 31, 20197 yr by LEOD

 

 

(edited out bad info)

fans may be coming on when the ECU detects open circuit ???

 

 

 

Edited February 4, 20197 yr by 1 Lucky Texan
wrong info

Do the fans run if you turn on the A/C ? 

I think by '02 it was all in one sensor.

Is the car getting hot? In the winter, it'll have to sit idle with the heat off for some time to get hot enough to require the fans. The main fan on our H6 Outback was seized, and I didn't even notice until some very slow offroading.

 

I don't know the resistance values. But I tested mine just with an OBD II reader. After leaving the car sit overnight, the coolant temp reads about the same as the intake air temp, and while driving, it sits at about 185*.

It is the three wire sensor for the ecu, the one that's a bugger to get to. I do not have the AC charged right now, so I have not turned it on. The fans and relays are clearly good as the fan energizes when the sensor is unplugged. Temp gauge goes to the red. All I can think of to do is part swap( expensive hit and miss) I will go to the Subaru dealership and buy the factory one, which may well have been made by the same company, bosch, and see if it works. PIA

58 minutes ago, LEOD said:

It is the three wire sensor for the ecu, the one that's a bugger to get to. I do not have the AC charged right now, so I have not turned it on. The fans and relays are clearly good as the fan energizes when the sensor is unplugged. Temp gauge goes to the red. All I can think of to do is part swap( expensive hit and miss) I will go to the Subaru dealership and buy the factory one, which may well have been made by the same company, bosch, and see if it works. PIA

 

Fans will run when the ECU sees a temp sensor fault.

It's traingular.  Check that you have the tab in the correct position.  

Beyond that return it and get a new one.  Try a napa higher end brand.  It will likely be an OE sensor in a branded box for less money.

Yep, 3 pin sensor serves for the ECU and gauge. So it's exposed to the exact same temperature, so a calibration issue seems most likely. But I don't like to encourage just swapping parts without diagnostics.

 

Any codes? I'd point an infrared thermometer at the coolant bridge and verify actual temperature. And then read the temperature at the ECU  via an OBDII reader. You can buy an infrared thermometer and OBDII dongle (read codes and temperature from you phone) on Amazon for $30-40 combined.

sometimes pins get 'pushed-back' inside connector housings.

Thanks to all, I put in a sensor from dealership and it works now, but the connector fell all apart, not fun, so, it could of been the old 2 things at once again.