Hey guys, i have a 2011 IS 350 with F sport exhaust (or whats left of it). So about 3 years ago I had an exhaust leak in the flex pipe (no code was thrown here). I went to an exhaust shop which fixed it and asked if i wanted my secondary CAT removed. I agreed. No issues here. Then about 2 years ago i made a dumb mistake by driving over a curb. It was snowing out. It was very shallow curb which i didn't see. I heard a very mild thud. Within 2 minutes my CEL came on. Code was P0430. Went to a Lexus dealer the next day and they said it was the catalytic converter. They replaced the exhaust manifold bank 2 under warranty. No codes came up for about a year. Now starting early 2019 i started to get a P0420 code i went to the same exhaust shop and turns out i had a leak at or near the resonator. So i replaced it. The code went away for a couple months. Then it would come back about every month but i would clear the code. I finally went to lexus again to get it checked out. After i told them the issue they told me they would have to do an "extensive test" and cant take my word for it. okay fine. $135 later they say exactly what i knew. They said they exhaust manifold needs to be replaced (bank1) with the AF sensor. $3300+ tax = $3729 CND. Are you kidding me?? Something tells me that they didnt do an extensive test and just checked the code and told me to replace it. Obviously i refused the work. But now ever since lexus touched it the CEL comes on every 2 days at most. Can anyone help me detect if in fact the exhaust manifold is the issue? How can both the Left and right side of the exhaust manifold go? Can it just be the sensors?

I have noticed that if the road is bumpy or i has dips in it the CEL will come on quicker.

 

I would start by replacing the cheaper items first and see if that fixes the issue...the O2 sensors, all 4. This is of course assuming that your exhaust system is truly sealed up tight with no leaks.

 

Since your in Canada. I'd say judding buy your resonator replacement. You have a good case of corrosion going on the pipes.

Start by having you exhaust shop check for leaks after the down stream sensor. They might have to knock of the shields that are in that area.

https://www.clublexus.com/forums/is-...e-leaking.html

 

If you're in Toronto and need exhaust work done I suggest Hot Rod Scotts on Kipling Ave.

 

That's exactly where I got it done. I found them kinda pricey but it's better then 4 grand just about FFS!

 

I'd go back and have them checked for leaks, it might be a flange or manifold gasket and the job can cost $200-300 vs. an arm and a leg at the dealer.

 

Are all 4 sensors identical? Do they need to be OEM or aftermarket?

I will read this thread thanks!

 

If i go back this would be the 3rd time to check for exhaust leaks. What do I have to tell them exactly in order to make sure there are 0 leaks??

 

Stick a piece of rug into the rear mufflers, start the engine, get yourself soapy water spray bottle and start spraying entire exhaust. If there's a leak you should be able to see some bubbles (hopefully).

 

Find a shop in your area with a smoke machine.

 

Thanks guys. I will report back as soon as possible!!

 

No, they're all different part #s because though the sensors are probably the same, the wiring pigtails are different lengths. Stick with the Denso brand. Reasonably priced Denso O2s I've found on eBay and Amazon.

 

Watch out for fake O2 Sensors...if they are too cheap, probability is that they are fake. Good luck, if you do a search, you can learn on how to tell real OEM parts.

 

Thank you again! I will have to wait for some warmer days ahead of me to do these repairs. Without you guys doing the work for me... Can you refer me to a link i can find all 4 part numbers for each sensor?

 

https://www.clublexus.com/forums/is-...r-numbers.html