I know that's probably a juvenile question to most of you, but I can't seem to locate them. I just bought my '98 Blazer LT 4dr 4X4 in August with about 103k mi. I'm at 110k now and last week my "Service Engine Soon" light came on. From my past experience, when that light comes on, it's either the O2 sensor or converter. So when I ask where are the O2 sensors, I'm hoping it's before the converter. That way I can be somewhat sure it's the sensors.

Also, I get roughly 250 miles to the tank with mixed city, highway (and led foot :D) driving. Is that normal for this truck. I don't expect to get great gas mileage since it's an SUV, but the reason I chose the Blazer over other trucks was because of power and fuel economy (if you can say that about a truck).

Thanks in advance.

normally located near catalytic convertor. You can go to autozone.com then shopping, then component location for your specific vehicle. best of luck.

there are 3 to 4 one on each of the Y, one before the cat, and one after the cat. but before you replace anything go to an auto parts store and have them test it, its free and saves you money if you buy the wrong part.