ecuwil

Last week I sold my 1995 LS400 that my parents bought new when I was in high school. There were never any major issues that I can remember, not even a check engine light. When I sold the car last week it had 260,000 miles on it. Saturday I bought a 2004 LS430 with 82,000 miles on it. One previous owner with all service records. The previous owner purchased the car and had it serviced at the same Lexus dealership along with a clean carfax.

Sunday night, just over 24 hours after purchasing it, I am driving down the road and the check engine/check VSC light comes on. Run the code and it comes up P0430 Cat. Syst. Efficiency Bank 2. I have ordered the up and down stream O2 sensors from Rock Auto and hope that fixes it.

Looking for a little encouragement and I might be over reacting, but things have not started off well with the 430. At this point I miss my LS400.

SC400slide

iTrader: (11)

FYI, o2 sensors are nothing. Lexus car's eat through those like captain crunch goes away at our house! You miss your LS400 because you never had a problem with it. So the car you loved mad a standard for you, and than an LS430 comes along and breaks a tiny something, and you expected nothing to break for at least another 100,000 miles, Right? Sell the LS430, and get a Ford Tempo. THAN, you will appreciate the luxurious vehicle you own! If that was a Ford Taurus I doubt the CEL would have illuminated as beautifully as Lexus! All your Lexus did is lost it's laces, in the long run, it's just getting started.

Lynzoid

It's not the o2 sensor. It's cats. You will either need to hollow them out and add o2 sensor spacers (to 'fool' the ecu), or get new cats (expensive).

Congrats on good buy!

SC400slide

iTrader: (11)

^But it will be worth the purchase in the long run!

DaveGS4

iTrader: (2)

Just to confirm you didn't fuel up and happen to not close the gas lid fully did you? I'm not sure what code that throws but it does light up the CEL.

Lynzoid

P0430 is 'right bank catalyst ineffective' code. Nothing to do with faulty o2 sensor. Again, it's the CATs. at 80k miles it's normal for it to go.

Oh! And DO NOT order stuff from rockauto for your LS!!! It's not a.... 'Chevy' ffs. Use only Toyota parts!!!

ecuwil

I am investigating all of the probable causes for the code that I have located by searching the forum.
Gas cap was checked Sunday night, I have an appointment tomorrow to check for exhaust leaks and have ordered the Denso oxygen sensors if needed. If the codes are still present after all that I will explore the most expensive option of replacing the cats.

Thanks for the feedback and I will report back as things evolve for future reference.

Gannet

The LS430 is a wonderful car, and fully as reliable as the LS400. That said, things can and do go wrong with any car, and if you need a cat, well, that's unfortunate but stuff happens. You're on the right track to change out the O2 sensors first, as of course that's how the car determines that there's a problem with the cats.

There's nothing wrong with buying parts from RockAuto as long as you know what you're getting. I get my Denso stuff from them, and I believe it to be the exact same part as the one in the Toyota box. I do agree that you generally are better off sticking with the OEM parts (Denso is the OEM for the filters and most electrical stuff on the cars). For the cases where you need Toyota parts, try Sewell Lexus. If you register there, and then give them your Club Lexus username, you will get serious discounts. Plus super-fast service.

I wouldn't expect this to be the start of some parts-replacement nightmare. There may be an initial period where you have to change a few things. First, because that's common when you get a "new" used car, and second because at 82k miles you're at one of those life-points in the car where some things will need replacing.

I would go through the car, change all the fluids, inspect everything, and then just keep up with it. At 90k (or so) you have a timing belt due. Based on past reports that rating is conservative and I would be comfortable going to 100-120k or so.

Lynzoid

Ok, you're decided to go thru 'long' route. I (and many ls owners) went thru this. Yes, exhaust leak may cause p0420/0430 BUT it have to be so severe, that your car would sound like a diesel truck.
DO NOT replace UPstream sensor as it's working fine! Especially with crap from rockauto (do not, again, DO NOT use aftermarket parts on LS430!!! Although Denso is OEM toyota and is OK!).

I did hollow out the cats and used 20usd o2 spacers from ebay to fool ecu into NOT displaying p0420/0430. 2 years and it's still never appeared again.

94GS300

OP, I know where you are coming from... I have a 1994 GS300 that I have had for 12 years and it is about to turn 200,000 miles soon. Nothing has really gone wrong with that car. I just do routine maintenance and it just keeps running like a top. It is ridiculously reliable.

The ONLY bad thing about having a car experience like you and I have had is that with your next car the only place to go is down. Your next car can't possibly compare to your last car experience. However, you have to look at it from the point of view that if you kept your old car odds are something was going to go wrong at some point with that many miles and how old it was.

Did you buy your LS430 from a dealer? I wonder if they had the check engine / VSC lights come on when they got the car and they just cleared the codes instead of fixing it. Just seems like a huge coincidence that you would set a cat code almost immediately after buying it.

Anyways, the LS430 is a wonderful car and hopefully once you get this problem sorted out you won't see anything major. Most of the things that go wrong are just minor things that don't need immediate attention.

Lynzoid

Yeap, can support that notion - if you clear cat code, it won't pop up for a day or two, but will pop nonetheless...

jay33

If you just bought the car from a Lexus dealer i would go back there and explain what happened and try to get them to address the problem before shelling out money out of your own pocket. Very suspicious that the problem developed immediately after the sale. Normally dealers give at least a 30 day warranty. It's ceratinly worth a try.

ancdmd

Just because you get that code doesn't mean it's the cats or the sensors. You have to check WHY it's throwing the code. From what I understand, the code shows that there's an out-of-range composition of the gases in the exhaust. This can be caused by numerous things, not just the cats or sensors. It is common on this car to develop a small exhaust leak in the y-pipe so it would behoove you to check that first. Just because it sounds normal doesn't mean there's no leak. And no it is not common nor normal for a cat to be bad at this mileage, so don't assume it's the cat either.

Lynzoid

No, you understand wrong....
ECU monitors sine signal (sinusoidal current) coming from upstream sensors (indicating proper fuel trim corrections are being applied in cyclic manner), and compares it to reading from downstream sensors, expecting to see same sine, but much lower in amplitude, thus knowing, that there's actual cat and it works. When cats become ineffective, the downstream sine gains amplitude until a certain threshold, then ECU lights up corresponding DTC.
And yes, there may be a leak in the Y-joint and it's common, but cat starting to fail at 82k miles is nothing amazing.

ecuwil

Thanks for the feedback! I did not intend to imply that I was second guessing my purchase. I really enjoy the 430 and know I will for the next 150,000+ miles.

As an update, I picked up the 430 this afternoon and was told there is no exhaust leak. It appears that the code is tied to the upstream oxygen sensor but I was told it could be the cat as mentioned by Lynzoid.

Lynzoid: thanks for the input, but I think I will replace the cat instead of gutting the existing if the new sensors do not solve the issue.

94GS300: I did purchase the car from a dealer in MN. It is my understanding that in MN there is no 30 day warranty, the sale is as-is and I signed a document stating that I understand that. Plus the Lexus dealership is 6 hours away. When the code was checked today the local Toyota dealership said they could not tell if the code was recently cleared. Based on the service records and condition of the car I do not think the dealership was trying to hide anything.

Next week I will change both bank 2 sensors. If the CEL light returns I will replace the cat.

Again, thanks for the feedback and I will update the post as things progress.