2000 Venture O2

I have a 2000 Venture that has trouble codes that both o2 sensors are reading lean conditions and a code for multiple misfires on all cylinders. The van runs fine, but the gas mileage is not the best right now. Do you think that both o2 sensors need to be replaced or is something else... I don't want to change the o2's at the cost of $150 if I don't have to. I have tried finding when other people have changed their sensors, but haven't had much luck. Any help will be greatly appreciated.

Try replacing the front O2 sensor first. That's the one that affects your fuel mixture. The rear one doesn't affect engine performance.

I agree with AJT. I replaced my front O2 sensor at 94K miles on my '98 Venture, and mileage improved. It's tough to access, and an O2 sensor removal tool (~$10 at Autozone) is a good investment.

I'll probably test both of the o2 sensors and see what that gets me. If they read bad, I'll change both of them. Thanks for the help.

I also forgot something. When I first took the car to the dealer to have it put on the computer (cause the OBDII port wasn't working-- go figure.. blown fuse). Anyway, there was only the rear o2 reading lean and the multiple cylinder misfires. Then, I changed the oil and air filter, and now I have both o2s reading bad. I didn't know if maybe not getting the airbox to seal tightly would influence this or not. It was a pain in the ass to change and I don't think it is completely tight. I have the bottom tabs in and the air filter seated, but it seems to latch tight.