2001 Kia Sportage O2 sensor before catalytic converter

I had a similar problem with my '01 sportage. There are only two O2 sensors on the Sportage and the first one was located at the top of the exhust outlet accesible from opening the hood, the other is located just behind the transmission and is accessible from undermeath the car. Typically both O2 sensors should both be replaced at the same time.

When I had this problem I didn't replace the sensors because I didn't have the money at the time and was in the middle of moving to Oklahoma. After moving though I noticed that the check engine light went off after using a tank or two of "oklahoma gas". I asked a few people if there was a difference in the fuel blend and they said that none of the gas stations in Oklahoma use ethanol in their blends unlike most of the gas stations in Kansas which do.

I can only assume that because of the difference in blend, it causes the O2 sensor to react differently. If you have the ability, I would try to use a gas brand that doesn't use ethanol. If you don't then I wouldn't worry about the check engine light, and just take your car to AutoZone every month or so to make sure that it is only the O2 sensor that is causing the check engine light to be on. It'll save you alot of money.

They replaced the wrong O2 sensor, the owner of the shop replaced the other O2 sensor free of charge. Of course, two weeks later the check engine light comes on again but this time I had a vacuum hose leak. This was covered under my warranty, the Folger's Kia in Charlotte, NC lied to me about my warranty.

Never take your car there to get it fixed! I took it once for warranty work because there was something wrong that made it fail inspection, they kept it all day then called and said nothing was wrong with it. I got it reinspected, it failed again, they told me that the tire hadn't even been taken off, so they didn't even look at the problem. I took it to the Kia dealership in Wilmington, NC, they fixed the problem, under warranty, and told me that if I had driven it back to Charlotte one more time the thing would more than likely have broken and caused a major accident.