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Old 05-17-2013, 01:17 AM   #303
Fast_Freddy
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Quote:
Originally Posted by tisb0b View Post
I know this has probably been asked before. Since the stock header does have a cat in it and if one gets a catted front pipe along with an aftermarket header w/o a cat. How do you move the O2 sensor from the stock header into the aftermarket front pipe?
You don't. The first (primary) O2 sensor is a wideband sensor that the ECU relies on to maintain the correct air/fuel ratio. The second (secondary) O2 sensor is primarily there to measure catalyst efficiency and as a cross check for primary sensor accuracy. In the situation you describe the primary O2 sensor would install into the new cat-less header and the secondary O2 sensor would install post cat in the front pipe.

Although your catalyst efficiency will be reduced by only having the secondary cat, it should be enough to satisfy the ECU and you should not see a CEL.
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