Bad 96 Pontiac Grand Am gas mileage. Any...

[antiquecardboard]

...Advice? So here's the story of my 4 cylinder 96 grand am. Last summer the check engine light went on and I took my car in and the mechanics changed the O2 sensor. Two weeks later the light was back on and has randomly been on and off ever since. Over the last 6 months I have noticed my mileage dropping from about 430 miles per tank (15 gallons) to around 250. I've changed the air filter but nothing improved. The car seems to be running fine...even through the negative 40F winter of Fairbanks, Alaska. Currently my check engine light is back on but I am hesitent to take it back in because I am afraid to shell out another $500 bucks for a new 02 senser that does nothing. I have spent some time on gravel roads with very fine dust--could that cause any problems...such a clogging random things? Is there any way to obtain check engine codes without taking it in and getting charged $150 just to have it plugged in and read? I'm no mechanic so any advice would be appriciated.

 

[Goatman]

First i would see if you have any parts stores near by that have code readers, I would think even in Fairbanks there should be something like a Autozone or simmilar place that offers a reader/ scan service..
secondly if they replaced the 02 sensor did they say why it went bad ?
usually the fact that it is getting poor mileage would tell me that something is a miss in the fuel system (sticky injectors) or possibly a bad coolant temperature sensor telling the computer it's still way below Zero even when its not ..
That will ruin a 02 sensor by richening the fuel system to keep the car running in colder weather ..
when it's not cold it just floods the system out and causes driveability issues,
also I don't know what the rates are up there (im asuming everything is more) but $500.00 for an o2 sensor ?? that seems a bit expensive !!
the only thing I can suggest is to find someone to scan it (dealers down here offer a FREE scanning service in most cases) with the GM Tech II it only takes a couple of seconds (literally) to plug it in and scan for codes if they are charging you $150.00 you are getting HOSED I don't care if it is Alaska..
GOOD LUCK !