1eltaino

Hello everyone.
Well let me start off with saying that this has been a big headache.Ive been trying to clear code p0430.I was told by mechanic that all my sensors are good,witch now its hard to believe.I first started with the manifold converter that needed replaced, check engine came back on,then I changed rear cat and resonator that needed replaced,the check engine came back again..what could this be??could it be a sensor or what .ive read that this generation has issues with this type of problem,but geesh havent had any luck and ive been coughing up a good amount if money..to use that know about this issue know that it can get a bit pricey .anyone out there that can please help me out
Thank you

aneidiaz

I've had this problem with my 01' GS430 before. This usually happens when there is AN EXHAUST LEAK coming from somewhere either before or after your catalytic converters. Many times the mechanic will read machine and say o2 sensors are reading fine. But only good mechanic really get under there and have someone give the car gas while its lifted up and they check for abnormal noises (loud truck exhaust sounds lol)... Well I was blessed with a good mechanic and this happened to me. Kept getting CE light on. Me, like an idiot went and coughed up $2500 for new cats from Lexus and all the GASKETS before and after cats. Come to find out upon finish that the old cats were still working. Yes they were old but they were still doing the job efficiently. So rule out CATS for last resort bcuz most likely you won't need new ones.... :-). Try this... Go to store and buy brand new gaskets for the cats BEFORE AND AFTER. Buy them double just incase. They only a few dollars each. Try going to Lexus dealer for them but any store is fine. If all o2 sensors are reading fine, just have a good mechanic replace all your gaskets and tell to please make sure there's no more air being released from ANYWHERE on the exhaust when car is on. Should be an inexpensive job maybe like $200 all together. But it should SOLVE THE PROBLEM. When there's air being leaked out it makes the sensors go crazy. They're job is to read the temperature flowing thru your exhaust. That's why there's 4... When there's a leak, any little change in temperature will set the CE light off. Yes that minor. But the car may be driving fine. This is a problem that CL needs to talk about more. These 4.3 V8s tend to have leaks over time. I'd recommend doing this every 12 months to keep your car running quiet and light free. You can hear an exhaust leak as well. Give your car gas in Park and it should sound like a raspy back peddling sound smh. If for some reason you ever change your o2 and is still not reading, have mechanic check your o2 wiring to the harness. I'm also telling you this bcuz I changed all mine all together and one didn't work. I was mad after all that money spent that CE light still came on. Upon careful review my mechanic seen my wiring to my bank 1 sensor 2 was corroded. He soldered them up nice and taped it up and never seen the CE light again! Hope this helps! I know you have a GS300. They still have these exhaust leak problems. Different engines same procedure. GodBless!

1eltaino

Hey man i appreciate your help.im going to try looking for a better mechanic,but everything is new in the bottom all new gaskets man idk

1eltaino

Although i am going to try to get a good mechanic to check the o2s and wiring .anf overlook the gaskets..but i literally have done from the manifold all the way back to the mufflers brand new so hopefully i can get this figured out and i can find someone good to check it without charging me a arm and a leg..the mechanic ive been using is pretty good and does the work in a garage with a hydraulic lift and charges a fare price under the table but i gueaa he just dont go through all tje procedures..I do want to thank you for your help and i will keep u updated once issue is fixed