eternal981

on a 2000 Mustang GT, do the O2 sensors start giving readings right away, or do they have to warm up first?

and do bad O2 sensors ALWAYS trigger a check engine light, or can they go without throwing a code?

mustang_montana

usually takes a few seconds to warm up, i think 20 seconds or so. havent had bad o2s, but usually if there' something wrong they will throw a code for bank 1 or bank 2 (front/rear)

eternal981

so its a safe bet that i can rule out O2 sensors as the problem for my huge misfiring problem.

or at least push it to the back of the line. it doesnt start until it idles for a few minutes and reaches full temp.