New wrx owner here, I just bought a 05 WRX a little less than a month ago from the local subaru dealership. This car had just come off lease and according to the dealer the only modification done to this car was the window tint. Anyways at lunch today the check engine light came on. Everything seems to still be running fine, but after work I took it by autozone to have the code read it cameback with P0172 System too rich (Bank 1). The guy told me it could be a bad O2 sensor or that if I had put gas in the tank recently that I might not have tighten the gas cap up.
I told him that I hadn't filled up in over 2 weeks infact I was down to 1/4 tank and planned on getting gas tomorrow, and while I was at the dealership they told me repeatidly to make sure the gas cap was secure. Anyway his suggestion was to buy some gas additive and fill up to see if the light goes away. I took this as him trying to at least get a sell out of this and said no thanks.
I'm probably just going to put a bit of gas in tomorrow see if the light stays on and on Saturday take it in to the dealership, but before that I just wanted to check and see if there were any other suggestions that you guys had.