p0420
 

Got this code about 2 months after installing JDL catted headers.I got them catted so that i wouldnt have the code. Ended up having an exhaust leak. fixed it and it went away for like 2 weeks and now its back. Theres no leak so do ya'll think that it might be the O2 censors or what else can it be? Thanks

Basicly it the header, if the cat is not same as stock header you can get CEL P0420


Will I get a CEL code
If you go to catless header you will get a CEL code P0420 (cat efficiency) it may thak a while to show up though.
Even some catted headers will still cause a cel code
You can try O2 spacers or de-foulers but they will not always work 100%
The only 100% way is to disable the code in the ECU usually done in aftermarket tunes.
The Cel code P0420 will stop the cruise control on your car from working, it wont go into limp home or low power mode.
Can be reset by removing battery connection or using obd tool to reset. It going to keep coming back until you disable it though.

Why you get CEL Code when changing header

Integrated in header is a primary catalytic converter. Their is the primary 02 sensor before this cat and a secondary 02 sensor after it. The ECU compares the reading from both and works out if the primary cat (in header) is working efficiently. If it detects abnormal readings it will set CEL Code P0420.
a tune for headers will disable Cel code code P0420 as well as optomising parameters for a header.

Thanks. And there is no way to keep cruise control after deleting the code?

cruise control will work again as soon as you clear P0420 code.

Try the Vibrant 02 sensor spacer through ft86speedfactory.com. It comes with 3 orifice sizes, use the medium size one installed on the secondary/downstream 02 sensor. Cheaper than a OFT or custom tune. it was $32 with shipping.