Lexus IS Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter · #1 ·
context, today, i was just driving with my check engine light on (which to me i thought it was just the p0456 that i’ve been dealing with for a year now, but don’t have time to chase it down) but i wanted to just double check randomly today so, i stopped at autozone and pulled a new code in addition to the p0456 which was p0420 (pending) i know this code specifically since i dealt with it nearly a year ago when i went catless (obx) headers with spacers to get rid of p0420 and p0430, however like many aftermarket headers for this car, its never perfectly flushed when installed. i don’t smell anything coming from the engine bay BUT i do have a fat exahust leak at the bottom of the headers that connects to the y-pipe. my question is, why does p0420 just comes back up after a year of it off? what are some possible causes if it isn’t o2? would it be a header leak that causes it? and also its just 420 and not the combo of 420/430. i believe when i was checking the data on the scanner today for the o2 sensors, b1s1,b1s2 were between 0.8 at idle…so, i’d assume its not o2 sensors? any advice would help. thank you in advanced.

White Light Product Communication Device Gadget
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #3 ·
Because it is not a perfect signature going to the ECU all the time. You need a simulator to make it perfect. As for your 0456 it could be just a bad gas cap. Did you use an OEM cap?
thank you for the fast reply Solar! does Karl on facebook still make o2 sims? i might have to buy one then if that’s the case.

as far as my p0456, i have replaced my gas cap with an oem one and it didn’t fix the issue. i’ve read many threads to look at the hoses, check the VSV, and etc. but I’ve been so preoccupied that I have yet to do that, but I plan to soon. I’m not really bothered by it for the time being, but I will get on that!
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #5 ·
I wonder if the new code is just because of the (hack) setup you're using. I wonder if it's just a random fluke occurrence that will happen sometimes. I'd clear it and not worry about it unless it comes back quickly.
see, now since my new exhaust setup where i spent an extensive amount of research to where i would not have the issue of having the codes thrown and have no exhaust leaks (which i still have that darn exhaust leak at the y pipe and headers) i drove the car for over a year without the p0420/430. it took me one try and it worked with the defoulers. i think it may just be a random occurrence, but i have since cleared the codes and will work next week to fix that exhaust leak for good JUST for good measures. i will update this thread when i get the chance to drive it a few miles to see if it comes back or not.
 

·
Moderator
Joined
·
5,974 Posts
thank you for the fast reply Solar! does Karl on facebook still make o2 sims? i might have to buy one then if that’s the case.

as far as my p0456, i have replaced my gas cap with an oem one and it didn’t fix the issue. i’ve read many threads to look at the hoses, check the VSV, and etc. but I’ve been so preoccupied that I have yet to do that, but I plan to soon. I’m not really bothered by it for the time being, but I will get on that!
Yes Karl still does. It takes a while for him. Because he travels for work. As for the other. If you have replaced that many hoses. Has you had a good smoke test lately.
 
1 - 6 of 6 Posts
Top