s40 2001 check engine code points to slow response from oxygen sensor #1. After dealer service dept. replaced and replaced again, still causes check engine light with same code after aa hour of driving. What to do now?

Has the updated wiring harness been installed?Does your car have the latest softwara downloaded into it?If not have that done and that might take care of the problem.

I have about the same problem, light is on for a week or two then off. How much will the dealer charge me for the reflash, I can get the HEGO at the auto parts store?

I read post on here before that someone got charged $210.00 for the ecm upgrade.I don't think that is correct.We used to charge like $90.00 for the upgrade.That was just labor.They don't have to order software it is within the P.C.