Important or not.... it turned on last winter when it was cold, and eventually went away, it turned on again... it was cold, it warmed up and now it turned off again. The part is like $45 i think.. it it worth the $$ and effort to pop that baby out?

Depends on which DTC you have:

 

P0181 means temp sensor out of range, replace the sensor

 

P0182 is open circuit, connector or wiring open to sensor, or sensor itself open or out of spec.

 

P0182 is sensor circuit high, ECU not putting out the 10V to the sensor, wire shorted to ground, or once again sensor itself with resistance too low.

 

If it happens only at lower temps, I would lean toward the sensor itself being out of spec.

 

My $.02

it gave me P0181

The car has 167000 miles on it... i guess i could replace the sensor...

So i went to the Subaru dealer today to try and figure out this problem... it took them about 45 minutes to figure out what the hell the code ment (i had it printed out on a paper.. and they still couldn't figure it out). THEN i was informed that you can't replace the sensor itself, you have to replace the entire sending unit...which is anywhere between $330-$450 (greatt...) So i said screw that, and headed over to advanced auto to try and figure out more. The guy there had never seen this CEL before, so he called up the company that sells the sending units to them, and got lotsa' info. As many people know, the fuel sensor and O2 sensor work together to try and keep something like a 14.7:1 ratio, and if one of the components goes then it trips this CEL, so i'm thinking it's more the O2 sensor (cheaper fix), not the fuel sensor.

Does anyone know for sure how to check an O2 sensor? pop the plug and test voltages? I'm guessing this would be easier than opening up the gas tank and pulling the pump/sending unit out....