I used to give advice...now i'm asking for some.

My 1992 4Runner check engine light is on. I fixed the problem (O2 sensor re-installed). But i can't get the light to go off.

The manual says to remove the EFI fuse for 30 secs (more if the ambient temp is lower)...so we had the fuse out for almost 5 mins but the check engine light remains on.

I could understand that the light would come on after sensing a defect again...but it won't even let me turn it off.

Any suggestions ?

Try undoing the negative battery terminal for few minutes and re-installing it, that usually does the trick. If that doesn't then I think you might have another trouble code on your hands.

Thanks for the advice but the check engine light went out by itself.

As soon as the O2 sensor sent the right signal at the right time, the PCM reset itself.

Gotta love toyota. With my GM van the light stays on forever until you use your OBDII to force the reset....even if the problem was intermittent or 1-time only.