No, the MAF comes off the clean air filter to the engine and the O2 Sensors are located in the front of the
engine comes up to the engine from the exhaust manifold. Looks like a spark plug with a wire coming out of it.
That is the up stream O2 Sensor, you do have others (O2 Sensors) But most of the time it is the upstream one
that is the problem. I have 2000 Hyundai Sonata 2.5L and the O2 Sensor was on recall back in 2002, was replaced and has been replaced again in 2005. I have 6 on this car all together, 4 on the engine and 1. on the
upstream exhaust and one on the exhaust pipe after the converter.