Ppe headers installed and third cat delete now p0420 code please help
Thread Starter
Lexus Test Driver
Joined: Apr 2013
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From: Virginia
Ppe headers installed and third cat delete now p0420 code please help
Just got my car back today with ppe headers installed and a third cat delete. To my surprise the CEL came on with a p0420 code, which is something about the catalytic converter. Since I didn't touch the primary cats where the O2 sensors are housed, what could be going on? The O2 sensors were fine before the install. Any advice is greatly appreciated
Thread Starter
Lexus Test Driver
Joined: Apr 2013
Posts: 1,076
Likes: 13
From: Virginia
Car runs bad ***. More power through the entire rpm range, both high and low. I reset the code. I think my o2 sensors are old and confused by the new airflow. I may put some O2 spacers and maybe replace the sensors themselves. I'm just dissappointed to get a CEL..
failed inspection last week I just replaced passenger side sensor then passed inspection. do not use spacers. you don't have to replace sensors if no light. that happen when you reset it light out.
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Joined: Jun 2012
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From: Pennsylvania
Actually, the front O2 sensors are mounted in the headers and the rear O2 sensors are mounted in the rear Y pipe with the 3rd CAT. The front CAT's don't have the O2 sensors.
P0420 can typically be caused by 3 things : an exhaust leak, a bad O2 sensor or a bad CAT.
Due to the recent work on your SC, I would check / listen for a leak and verify the harness to the driver side front O2 sensors is connected at the junction ( engine compartment ) with no harness / pin damage. Also check the driver side rear O2 sensor harness.
Not sure how you effected the rear CAT delete, but if that sensor was removed and re-installed like the front sensors, then it's possible they were damaged. A good Scan Tool with real time O2 readouts will help define the problem
P0420 can typically be caused by 3 things : an exhaust leak, a bad O2 sensor or a bad CAT.
Due to the recent work on your SC, I would check / listen for a leak and verify the harness to the driver side front O2 sensors is connected at the junction ( engine compartment ) with no harness / pin damage. Also check the driver side rear O2 sensor harness.
Not sure how you effected the rear CAT delete, but if that sensor was removed and re-installed like the front sensors, then it's possible they were damaged. A good Scan Tool with real time O2 readouts will help define the problem
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Thread Starter
Lexus Test Driver
Joined: Apr 2013
Posts: 1,076
Likes: 13
From: Virginia
Thanks- I have an O2 scan tool, but what should I be looking for? Also, according to diagrams I have seen the third cat is after the o2 sensor so a third cat delete could not effect that sensor?
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Joined: Jun 2012
Posts: 544
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From: Pennsylvania
Depending on how the 3rd CAT was deleted. If they just cut it out and welded a piece of pipe in its' place, then the rear O2's might not have been touched . From the factory, it's one long Y pipe with a CAT after they join into one pipe, but it is one welded piece and the CAT does not have conventional flanged ends.
With the P0420, it's saying the drivers side, so compare the readings from one side to the other, both front and rear O2's. A bad sensor won't fluctuate like the others. Might be a YouTube video on it somewhere.
With the P0420, it's saying the drivers side, so compare the readings from one side to the other, both front and rear O2's. A bad sensor won't fluctuate like the others. Might be a YouTube video on it somewhere.
Thread Starter
Lexus Test Driver
Joined: Apr 2013
Posts: 1,076
Likes: 13
From: Virginia
They cut out the third cat. It's actually two codes: P0420 and P0430, so I guess it is both sides. Should I monitor the O2 readings on my scanner, and look if the voltage is between .2 and .9? I looked at several websites, and it could be a variety of things in addition to the 02 sensor. Makes sense given the extensive install. I hope my shop can figure it out at no cost. If not my first inclination is to install O2 spaces myself..
Good luck
Just got my car back today with ppe headers installed and a third cat delete. To my surprise the CEL came on with a p0420 code, which is something about the catalytic converter. Since I didn't touch the primary cats where the O2 sensors are housed, what could be going on? The O2 sensors were fine before the install. Any advice is greatly appreciated