Rear O2 sensors with headers question

I have just installed LG Pro long tube headers on my 03 Z06. I used HP Tuners to turn off the MIL errors (P0140 and P0160) and SES light for these codes since I do not have cats nor rear O2 sensors. I was looking in a product catalog last night (Mid-America) and it said you need to use O2 simms in the rear when you don't have cats - else "your air/fuel ratio will be processed incorrectly". I was under the impression that the rear O2 sensors were only used for emissions purposes to determine if the cats are functioning properly. Which is correct?

Mmmmm, good question! Ya had me going until I thought about it! I also have the LGs and I used the Sims just to stop throwing error codes with the missing rear sensors. :secret:

Sims are static, they do not change their output value, sooooooo as far as A/F ratio being right, the Sims are not going to be able to make it right. Well they might be right once in a lifetime. ;D

Nope they are just there to herd the cats! :huh2:

I wasn't suggesting that they made it right, but it sounded like they were saying that the stock rear 02 sensors functioned something like the front sensors reporting oxygen levels which the computer also used as input to adjust the air/fuel ratio.

I agree, but as far as I know they just are there to check the cats function and do not figure into any other calculations.

Rear O2s are only a watchdog for your cats and to tattle on you when you are storing your emissions compliant equipment in the trashcan. They make no fueling judgments.

They're kind of like my ex-girlfriend, they always have an opinion, but you never listen to them until they threaten to tell your mother...

John.

02 sensors do nothing but tell you when your cats are bad or one of the sensors have gone bad, the front o2's are the only ones that help control your a/f ratio.

Chris