I noticed a few weeks ago that while driving at about 55mph. for a few minutes, my check engine light will come on. When I let go of the gas pedal, the check engine light will shut off after a few seconds and will usually remain off for the rest of the night. After reading through the archives within this group, I came to the conclusion that it could be my oxygen sensor. I have also noticed that my gas mileage has dramatically decreased, and from what I also read, is a sign of a failing oxygen sensor.
I went to have it replaced earlier today and was told that there were TWO oxygen sensors for my vehicle. I was not able to locate a second one (there is one before the catalytic converter and according to the shop I took my vehicle to, there's one after). Is there one or two oxygen sensors for my vehicle?
Also, if I had the oxygen sensor replaced, would that likely cure the problem with my intermittent check engine light and decreasing gas mileage?
Thanks!!