04f2504x4

Just purchased a 1994 sc400. It runs great yet two days after buying it i get a CEL code. First 21 then 28. I searched and saw that means main.. then i believe the main one after the cats due to the 21 failure. So i looked up o2 sensors and wow pretty expensive for what i thought.

Is it possible to know which one of the main two is bad??? Does 21 mean a specific side? I'd rather just purchase one as i am a poor college student.

If not i would obviously purchase both. I am poor but i like to keep a good running car.

Thanks for any advice
Ben

matrixgts

iTrader: (1)

when i had mine checked out at the auto store they pretty much let you know which one was bad and it was free.but usually if one goes bad the others will fail shortly that's what happend on my 97 300.migh as well get them all changed out when you can.