CEL light on after installing intake -CO2 sensor code?
 

I just installed a new cold air intake (basic straight pipe w/ filter) on my 8, and after driving for a day the CEL came on. I reset it by disconnecting the battery, three days later, back on again. The code is showing CO2 sensor...is it worth changing back to my old stock intake? has anyone came across this before? just dont want to damage anything i know people have a lot of CEL problems.

what is the code? and what intake?

hey im not sure what the code is, autozone did it and told me it came up CO2 sensor. The intake is a spectre one, just a basic 90 dollar kit with a short nose cone filter. Everything sounds great, except for that CEL. On the intake the only thing i connected to the pipe was the MAF sensor..i didnt miss anything did i, all the tubes look like they are connected to the actual intake body behind the rubber flange.

Maybe the positioning of the sensor is throwing the code. Is your intake a "universal" fit or is it made for the RX8?
Also, with your stock box removed did you do anything with your VFAD just out of curiosity. Might be helpful to post a picture of your engine bay for us.

ill post a pic...im new to the rx8 so i might have missed something in my install. All i did was remove my stock airbox, by disconnecting it from the rubber tube heading into the intake manifold (left everything on the part with the flap; tubes, vacuum lines, etc) and connected in my new straight universal pipe with the cone filter. I reconnected the MAF sensor and that was it on the intake. Im getting confused with the VFAD no matter how much research I do... am i supposed to remove the whole housing with the flap and connect the CAI directly ahead on this closest to the firewall?? Ill get pictures to help if i can, but hopefully you understand what my setup looks like now.

Did you use one of the screens from the bottom of the stock air box in your intake. If not that is probably why you are getting a CEL. One other problem may be the size of your intake pipe. If its not atleast 3.5 inches (like the stock airbox tube) you are starving the car for air and will definately get a CEL. I learned this when I made my CAI. I initially used pipe that was 2.75 inches.....not good. My current intake consists of 4" and 3.5" aluminum intake pipe. If you cannot use one of the stock screens in your current intake go to Lowes and buy a roll of window screen. Stand the intake pipe on its end and cut a piece of screen (in a circle) at least a half inch large than the pipe opening. Once cut, slide a rubber coupler over both (screen & pipe). Make sure the screen is long enough that it is pinched against the outside of the pipe by the coupler. Put a clamp on the coupler and test the screen by pressing on it. My screen is under the coupler just in front of the MAF. The link below shows my current setup.

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/new-greddy-oil-catch-can-installed-125435/

its close to the same size, ill try getting one larger though and figuring out a setup like yours with a straight pipe and cone filter. Looking over my setup again, it looks like I dont have a VFAD..is this possible. From research on this site, it seems like the VFAD is located ahead of the stock airbox on the section on tube that heads down under the bumper towards that "fabric" section. Ahead of my airbox I just have a plastic pipe that curves down under the bumper and ends with a fabric mesh piece. I just bought the car, could someone have removed this?? maybe this is throwing off my sensors on my intake? ill work on pics

If you still have the stock intake pipe that runs behind the front bumper then you should still have the VFAD connected (unless you unknowingly disconnected it). Attached is a layout of the VFAD assembly (look at the bottom of the picture). The VFAD actuator is at the end of the pipe as it enters into the engine bay (just before the stock air box). If you follow the vacuum line, you'll notice that it runs all the way to the intake manifold. With some aftermarket intakes (like Mazdaspeed and AEM) you need to remove the whole VFAD unit and plug the inlet to the intake manifold or else you'll get a vacuum leak and it will throw a CEL.
Now if you didn't touched this assembly during your installation, then I wouldn't worry about the VFAD causing a CEL (but its also not really doing anything for you either). If you did remove some of the vacuum lines and/or pieces of the assembly (such as the vacuum chamber or the solenoid) then you'll need to plug the inlet at the manifold.

well apparently the last owner removed the VFAD and i assume blocked the vacuum tube...they must have had an intake, im not sure. Basically ive been running the stock airbox with no VFAD and havnt had any problems (CEL light) or lack in power. Now im stuck, the only thing i can think of is either i need to try a screen before the MFAS or a larger pipe. I know the stock airbox is fine, but the sound from CAI basic setup is worth it i think for now.

I wouldn't assume anything... best to double check.
Just past the throttle body on the intake manifold you'll see a "nipple" hanging down. Make sure that it is plugged.

Post a pic of your setup when you get a chance.

Here is the link to my very first setup. My current setup looks just like the first 4 pics in my original thread but with 4" and 3.5" piping. You should be able to fab one from the info I posted. PM me if I can help out.

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/custom-cai-wish-me-luck-103093/

close doesnt count when dealing with a MAF sensor. it needs to be the actual correct size.