After I had a Hogan Downpipe with the hi-flow cat and Magnaflow mufflers, i started getting the P0420 code, has anyone else had this happen and what have you done to fix it? according to a few websites, they recommend that I replace both O2 Sensors, is that the correct fix?


tony

 

This is really common, go hit up the search box and you will see the answer in many many places.

You can either get a tune, there is a mechanical fix, deal with it, get rid of the pipe, etc...

 

ya same thing happen to me, I just had the car tuned and they tuned out the code. Since then its never been back. I would try that first before changing the O2 sensors. Besides having the car tuned is the recomended fix from hogan themselvs. http://hoganperformance.com/DP7S.htm

 

Well see there's part of the issue, I bought the newer downpipe from Hogan, who assured me that this model doesn't throw codes, but i am still getting it, any recommendations on tuning? i live in Eastern PA and so far have not found anyone local who can do the tune, i thought about buying a superchips tuner, would that help my issue and provide me with a good tune?

 

I'd hook you up if you were closer. All you need to do is turn off the rear O2.

 

JDMC5,
How can I turn off the rear O2? i was looking at website to see if they offered one of those O2 simulators so that the computer would always see the right voltage and not throw a code, but nobody has them for an 07.

 

You need to put a spark plug anti-fouler between the O2 sensor and where it screws into the downpipe. You can them at most auto parts stores.

 

There's a shop just outside of Philadelphia depending on how far you are, that dyno tunes vehicles. They're all GM owners, if you want to go that route.

 

RedHotg8,
Thanks for that info, I will look into that and will keep my fingers crossed. I see you show a superchips tune, did that really make a difference for you, was it noticeable?

 

BigBlackBoxChevy,
I would definitely be interested, I live just outside of Philadelphia, could you please send me the name of this place and any other contact information for this place would be great.



tony

 

^ he is right a spark plug non fouler for 8 bucks will fix your problem and the superchips does work it not an omg this is a different car but it works

 

The Superchips might not work on your car but it turned mine into a totally different car. The G8 runs rich from the factory and the trans tune is awful, so it made a huge difference.

 

Not to mention torque management up the *** and weak 87 octane timing tables, like stated above. The G8 has one of the least agressive tunes GM ever used for an LS car. The TBSS and new camaro are also pretty bad. Now, the GXP as one of the most aggressive tunes so don't expect a big gain from a handheld for the GXP.

I use hptuners to turn off the code. There are several different brands of software that can also do it. Any speed shop that can tune your car should be able to do it.