Has anybody been able to clear the MIL after installing headers and a high flow cat? I have tried almost every solution that has ever been given to me. I have 4-2-1 headers, a carsound high flow cat, and a mbrp cat-back exhaust, all 2.25". I removed the muffler from the cat-back and put on a Raptor muffler with a tip. At first I was getting P0420 (I think anyways, catalytic converter efficency). I am currently playing with the O2 sensor simulator, but the ECU is not fooled. I am now getting P0138 (B1S2 High Voltage). Once during every trip the ECU leans out the mixture and checks that both O2 sensors drop below .2V (200mv) and I believe this is why the ECU throws the high voltage code. This condition may be right or wrong, but it is what I have gathered from the shop manual. I have searched on many forums (including this one) for many different cars and still have not found a solid solution. Maybe I am using the wrong words in my searches. My last resort will be to put the stock manifold on with the Calif. cat and sell the headers for way less than I bought them. Any advice would be greatly appreciated.

 

One o2 sensor goes before your cat, one goes after it.

Simple as that.

I have the exact same setup as you, but Catco instead of Carsound for the cat.

 

I have one O2 sensor before the cat, and one after the cat, but I am still getting the MIL. Does the second O2 sensor have be a certain distance after the cat to work properly?

 

No, my 2nd o2 sensor is actually in the cat, I bought the cat with a bung welded in the back right before the flange.

Do you have the sensors switched around possibly?

Is your car running fine, or does it feel doggish?

So your 1st o2 sensor is where, in the manifold or in the flex pipe? And where is your 2nd one?

 

My first O2 sensor is working fine. The car runs great and gets decent gas mileage. I have the first O2 sensor on the header, coming off of cylinder 1, I believe. My second O2 sensor is on the end of the catalytic converter right before the flange for the cat-back.

If you have a similar setup as mine, maybe the wires got mixed up when I extended them to the cat. I double and triple checked everything, but anything could happen. I get paid on Friday, so this weekend I am going to buy another new Bosch downstream O2 sensor (my third and final one) and re-run the wires exactly how they are supposed to be. I still have all the OEM connectors so I can match the wires by color. If this works, I owe you big time.

 

Only thing I can think of is that you may have screwed something up when you extended the o2 sensor wires for the 2nd o2 to reach to the cat. Did you use the same gauge wire? You heat shrinked and soldered right, not twist n tape?

 

Also, I notice you have a 99 tib. I have heard of people with the Turbulence swapping to the older Tib ECU. Think this might make a difference? I noticed that Redzmang has the earlier ECU for the Turbulence. Any difference in performance?

 

Wait a minute, Bosch downstream o2 sensor? Why did you upgrade your o2 sensors? Or is that an OEM sensor?

 

As far as the wires go, it is possible. I did solder and heat shrink everything, but between the harness colors, my wire colors, and the O2 sensor wires, something could have been crossed.

 

Some tibs are 1.8's, and others are 2.0's. If you have a 2.0 tib, you will receive some slight gains by swapping in either the 1.8 cam, or the 1.8 ecu, or both.

That however, has nothing to do with your issue.


Either your cat isn't doing it's job, or your 2nd o2 sensor isn't working.

LOL, any chance you installed the cat backwards?