Hi I have 02 GS300 with a p0430 code I have had 2 02 sensors replaced as well as a used manifold . I am being told it could be a 3rd converter help please .

 

Driver side upstream, if you have replaced both already, it may be time to do the cats,

 

thank you for your reply I replaced the two up front should I change the 1 in the rear ?

 

Yes change the rears as well. Although it says it would be upstream a bad O2 downstream can give off the code as well.

 

look if you have a exhaust leak ( even a really small one) at the cats flanges. I had the same codes p0430 and 431 and the really small leak there was enough to trigger the code. 2 gaskets and the problem was gone.. It's worth a look before you start changing cats lol

 

say there was a leak.. or tiny crack under heat shield. would a mechanic be able to physically hear it? under load / idling?

i have had a few of them check but no one seems to think its an exhaust leak..

2006 lexus gs430
code: p0430
loss in gas mileage (big loss)
mileage: 90k