jgwilson88

I have a 2003 GS300 with 160K miles. Check engine, VSC, VSC OFF lights came on this past weekend. I went to my mechanic yesterday and he said his computer is showing code P0430 which he says its for the catalytic converter and ill need to have it replaced. Has anyone else experienced this and what are my options? He quoted me at $625 for CAT and $140 for labor. When searching I've seen them from $400 and some change to $1K +
Thanks!

BiGEZ

iTrader: (24)

Have you changed you O2 sensors? I changed all 4 sensors with new OEM Denso units and that fixed my problem. I have 190k miles on my original cats, no codes.

jonathancl

At 180k I had p0430 and p0420.

I had holes in the exhaust that I had patched, and then I only had p0430, which I fixed by replacing one o2 sensor.

I still have one o2 sensor for sale, may be what you need.

MedicalDoc

Which cat? There is more than one so this diagnosis is suspect. Have you tried clearing the code and see if it comes back? Do you have an exhaust leak? I agree with BiGEZ but would rather clean each O2 sensor, one at a time, and check to see if the code comes back--they are not inexpensive--. Lexus' converters are durable. Unfortunately, aftermarkets cats are not that reliable according to other CL members (tons of posts on the subject if you search). Also, I agree with OEM sensors if you are going to change them.

k1ng

Agree with everyone else. Start with the most simple fix related to the problem. o2 sensors and check for leaks. Then work your way to the cat system. Usually pre-cat are the ones first to go P0430 I believe is pre cat drivers side. if code comes up again, replace post cat. This is assuming you have checked your exhaust system for any leaks.

jgwilson88

no I have not changed any sensors. I thought that may be what it is and not the cat. It's just hard for me to believe that the cat has already went out with only 160,000 miles. He says it's from all the ethanol in the gas and it has ate the honeycomb out of the cat. I was going to take it back to him today to let him look at it a bit closer for a few days when he can get around to it but the codes have not came back on since he cleared them out.

jgwilson88

from what he told me the code was showing bank 2. He said that should be the If you were looking at the motor to the left it is the cat that is lower. I hope that makes sense. I have not noticed any type of exhaust leak and do not hear one. I was going to get him to check that if he could get it up on his lift. He recommended me to a local muffler shop which I called today and he said he could replace that catalytic converter if I was for sure it was that one with the replacement. Said he could cut the old one out and weld in a new one. Said parts and labor on that would be $300. I'm thinking if I plan on keeping the car I might as well replace the whole piece with both of them on there because if one has gone out I'm sure the other one will not be far behind. I guess I will continue to drive it like this and see if the code to come back on. It's not my daily driver so I usually drive it on the weekends. I've drove it probably around 10 to 15 miles since he cleared the codes and They have not came back on yet. Hopefully they won't. The only other thing that makes me wonder if something else is wrong is that from a stop position The exceleration just doesn't seem to have a get up and go that it should, But from a roll or if the RPMs are up some it seems to have the power than it should. This is the only GS300 I have ever owned so I'm not sure if that's just how they are. I also have a 2009 GS 350 but I know I can't compare the power against it.

kevin3344

Chances are you have an exhaust leak. When I got my P0430 code on my GS the CEL would come and go for a while...off and on...eventually the dealer said it was my y-pipe (common on a GS4). Keep in mind just because the code says "Catalyst System Efficiency Below Threshold (Bank 2)" does not necessarily mean it's your cat.

Alphaman19

Had same codes, issues. Was running on the original o2 sensors and found that my ypipe had a leak.
Replaced all four o2 sensors and a new y-pipe.
Problem solved.

GS400 with 298k

alexulan

i believe i had the same code it was some smog little rubber hose by the firewall broke in two (car was 16 years old).
Simple fix took 4 diffrent mechanics to find it. Cracked so clean that didn't even look broken.

MedicalDoc

jgwilson88,
At the risk of sounding repetitive, I agree with the last two postings. The 03gs300 cat comes integrated with the manifold at a cost of, according to lexusofwarwick.com, $3791.95 --labor and exhaust manifold gasket not included--. Your two quotes, with labor, of $765.00 and $300.00, are suspicious in my suspicious mind. I really would repeat getting under the car, have somebody rev it up and check the heat shield (specially where it meets the pipe) and the gasket between front and center pipe. BTW, that is where my 02gs430 had the leaks--I didn't notice the gasket issue until it was revved--. If you have a scanner, just for the fun of it monitor short and long term fuel trims as well as O2 sensors. This will give you an idea of how the car is doing. In my case it confirmed that I was running rich and burning too much fuel (some soot in my exhaust pipes when I gave it a "pipe exam"). Now, my mass airflow sensor had also gone bad. Coincidence?? At least I didn't spend $200.00 plus for each O2 sensor. I hope this helps. Please let us know.
This is the link,
https://parts.lexusofwarwick.com/a/L...M/8909185.html

shboni

iTrader: (2)

I literally did this fix today. Got the same CEL PO430
It is an O2 sensor, did this same fix back in 2013: https://www.clublexus.com/forums/per...o2-sensor.html
Most likely it is the sensor........... but definitely DON'T pay that mechanic that is a rip off
That is a $60 dollar part from Rockauto.com and an hour or two of your own time

MedicalDoc

Shboni,
One question, if you don't mind. I read your December 4, 2013 post where you hinted that you were going to change all four O2 sensors on you 1998 SC300.
(Heck I might as well order the other two sensors but it would still be cheaper than ordering one sensor from Swell ).
Were all four finally changed? Denso, I believe, is OEM for Lexus. I can see them going bad after 15 years, but not after four. In any case, that was a great price for them. Johnson Lexus lists the O2 sensors for something like $166.00. Thanks.

silverbul

Lemme tell you what I did back in January wen my vehicle thru codes similar to yours & I thought about changing my cats. Saw an old trick on YouTube where the guy uses lacquer thinner the clean out the fuel system. So what I did was drove my car unti it got on 0 miles to empty. Poured a whole gallon of thinner in my tank then filled the tank to a half a tank of premium fuel. Just drove around until I burned that whole mixture out. All my codes went away, all the lights went out & the car went back to normal. Thinner has a few more solvents than regular gas treatments. Thinner cleaned any water/moisture buildup in your tank, cleans your injectors, spark plugs along with the 02 sensors and your catalytic converters. Here it is July 25th, 2017 & I haven't had problem since I used that method. $18 gallon save me $$$$

MedicalDoc

Brave person you are!