I have a '96 SE Auto with 93,000 miles on it. I have exhaust, CAI, etc. I installed an A/F Ratio guage awhile back and hooked it to the O2 sensor on the forward exhaust manifold. No problems. Today I got another one to hook to the O2 sensor on the rear manifold. I want to monitor both of them. My question is, is it bad if they aren't reading the same all the time? The one on the rear seems to react about a second slower than the one on the front. Is this cause for concern or does it sound normal? If I were to watch each one by itself, they seem to act normal, but both of them at the same time is different. Does this sound okay or should I get it checked? Thanks.

 

I don't think you have anything to worry about. There is no reason to expect that the two readings would always be synchronized. As long as the Oxygen Sensors are doing their job, don't worry, be happy.