I have owned my car (2005 ultra) since 2009 and gone to Lexus dealer for repairs except things like oil changes. First 6 years the car was CPO + 3 years Platinum coverage, so covered (all minor like telescoping wheel motor, etc.). Only other issues since then were one new wheel bearing and new water pump (not at dealer since I could not drive car that far with no coolant, so took it locally!)

Check Engine Light went off in July, and I went to dealer. Needed 1 cat, then in August, got 2nd CEL and was told I needed y-pipe and possibly O2 (turns out I did need both as y-pipe was not enough to fix it). I was already wondering if the cat was never really bad in first place, since if O2 sensor was bad 1 month later, how could it measure that cat? But dealer says they are different codes, etc... they have their process, alas... I did both repairs at dealer and chalked it up to price for a 14 year old car that I still like...

Now my CEL just went off a third time, just 3 months later. Thinking dealer is too much $$ and do I need true OE/OEM parts, I called a local repair shop They told me to bring the car by to look and check the VIN for a proper cat (IF that is what it needs) but that they would order it from Lexus... Why not a legal 3rd party cat, I asked (like Rock Auto or whomever they source from)? Answer: "3rd party cats don't work on Lexus".

So, my q's:

(1) what are peoples experiences with this price-wise for the cat if not doing it themselves ?

(The dealer charged me $1500 (!) for one cat, which seems like a lot but might not be unusual.)

(2) Is the mechanic right that he really needs to get the part from Lexus? 3rd party cats no good? I mean, I see them on rockauto or whatever...

I love the car (2005 Ultra) and have had no reliability issues ever that left me stranded, so if I need to put in another $1500 for a 2nd cat, I will., if that is the source of the problem, and hope I am not starting the spiral of doom on this car (I don't think I am!) The thing is, I was thinking it is time to skip the dealer for repairs on a 14+ year old car, yet the need for original parts means I might not save much from the independent mechanic.

(3) Also wondering if the dealer's original cat diagnosis was right (on the first cat), given that the o2 sensor failed right behind it... wonder if they should have replaced the O2 sensor first, but the intial code (p0430 if I recall?) told them to do the cat... is anyone "smarter" in diagnosis to check O2 sensors first, or do I just have to live with it?

I keep cars long and have had big repairs on other cars in past, like $1800 for a trans rebuild on on old car, but 3rd CEL light in 4 months is getting frustrating (assuming it reads as the 2nd cat this time) and the dollars are adding up. I keep hoping "this is it", but wondering if the next o2 sensor is right behind, etc.

FWIW The car is federal emissions standard, not NY, might affect which cat goes on it, not sure... and I am not a DIY kind of guy on cars, which I know would save me a ton.

Thanks!

 

An aftermarket catalytic converter would be fine to use, I don't have experience with them but there is no reason it has to be an OEM part from a dealer.

How many miles are on your car? Depending on how they do inspections you can usually get the CEL to turn off by intalling a spacer on the downstream oxygen sensor. Installing the spacer doesn't fix the catalytic converter instead it changes the downstream sensor's reading enough to usually turn the CEL off. This could be illegal in your area so do some research first.

You really should buy yourself a code reader, they can be had very cheap and help you make a more informed decision the next time you have to visit a shop.

 

The Y pipe rusting out is very common, happend on my 04 with only 123k on it. I replaced it myself with the Davico bought from Rockauto.com for under $300. The labor is not difficult, it would be much easier if you have access to a lift.

 

Thanks for the replies. I may buy a scanner. Someone did scan it for me and I got back "running rich on bank 1," but not sure if that could indicate a cat problem vs another O2 sensor, etc. They would have to diagnose more, they said. (Don't have the exact P... code). Ironically, when my O2 sensor went bad with Y-pipe, dealer told me than I had a LEAN condition code, but not sure it was on same bank, etc... I believe the cat that was replaced was on bank 2. I wish I were more mechanically inclined to diagnose myself... as in, WHICH O2 sensor was replaced and is this relevant the the issue at hand, etc.. I can be diagnostic (I do I.T. work) but don't have the data here, so am at others' mercy here.

I don't know if that could be cat or something else, but I guess I will bring to dealer as they said they will check it without a diagnostic fee, in CASE it relates to the recent fix I had. But if it is unrelated, they might charge me if I don't do the work with them, so a bit messy situation. After this "cycle" of fixes is done (no more CELs for, say, at least 6 months) , it is definitely time to find a good local mechanic and be done with dealer for major repairs, but finding one I can trust who is both honest and not sloppy is not easy. I have had so few actual repairs (just a water pump and 1 wheel bearing in last 4 years) that I have simply gone to quick lube places for oil changes and dealer for other stuff (brake fluid replacement every 3 years, trans fluid change at 90k, etc.). But the pricey Cat did get me thinking it may be time for an independent.

 

An update on this (CEL light going off 3rd time). I saw a separate thread on vsc/CEL light recently, but that seemed more on how to jump the obd ports to turn it off, so I will continue to post here instead. I did bring my car at dealer for this issue, since I had the other two exhaust-emissions repairs so recently (stated above). I am not handy and assume there is SOMETHING really wrong with the car with the code I am get (running-rich). The upshot is, my car has been at the dealer over a week(!) with no real update, even when I called. The first day I spoke with the actual technician (vs the customer rep) who told me Lexus' flowchart on this was complicated and that they needed time to figure out it, with the end-state possibly be needing a new ECU (wow, really? Car is find in all aspects except for this light going on). There was a possible MAF sensor path along the way... hope that would be cheaper.

But I called after 4-5 days (late last week) and got some answer about an maybe a MAF and said they are still diagnosing it I didn't want to be pushy (the rep really just said nothing new, be patient). but I was wondering how long a diagnosis can take? Surely they aren't working on my car for a week straight, I would be broke and/or they would be! Are they trying things, waiting for testing parts to try to swap? No real answer I, but I wonder what an indy mechanic would do in this case and it if would be better or if I would have same issue. Not sure now confident that dealer can get a handle on this via following printed out diagnostic flowcharts... I mean, this COULD be right but just seemed a bit boilerplate to me, so I wonder what other approach an experienced mechanic would take. How this turns out will affect if I keep the car and if I continue to go to the dealer. I love the car but need reliability of not worrying about having an issue every 2 month. I don't mind paying for expected aged parts (say starter or door lock actuator if it went bad) but the uncertainty on this is not good. Just sharing. My parents had an LS400 with 180k miles and I know many go way past that. I am only around 140k myself, but the car is of course 14 years old, and I need to clear this hurdle... hope I can.

 

A leaky exhaust can cause cel's also the type of gas can make a difference if you have super crappy gas with water in it your car will lean out.

Also use lucas fuel injector cleaner maybe you have a clogged injector. Quick question when you go above 2400 rpms with mildly agressive acceleration does your car smell super sulfury or super gassy? Gassy means its running to rich and sulfur means its not getting enough gas leaning out and heating up the cats to crazy hot.

Also did the ding dongs at the dealership check to make sure the o2 sensors are not coming unplugged from the harness stupid question but it could be the gas of an intermittent cel if the wire has a semi brake in it some were.

 

Just an update from me, its been over a month on the Davico Y pipe and it's been working great. It's only a secondary cat inside the Y pipe anyway, so you don't even really need it. In hindsight I should have punched out the secondary cat when replacing the Y pipe.

 

Okay I'll try and help form the perspective of being a mechanic who is used to dealing with Lexus and BMW/merc emissions and sensors.

The first step is to pull the sensors off the harness and ohm test everything to make sure the harness and sensors are in spec and if not then replace the sensors in pairs since they almost always go or at about the same time. The upstream sensors (you have one per bank of cylinders) are responsible for determining fueling ratio and telling the ECU if more or less fuel is needed vs requested operating state and environmental variances. This is compared to the injector requested duty cycle and fuel rate as well as the air volume checked by the MAF sensor, the computer is able to use these points of information to adjust everything exactly where it wants to and also determine if something is wrong somewhere in the system.

For example if you required 80% throttle and the ECU checked it's learned map and sent the command to open the blade for that amount of acceleration (depends on how learned the car is to you and a bunch of other factors) and sees the MAF sensor showing a very low amount of air coming in but the injectors are firing normally per the map and the upstream O2 sensors agree the combustion ratios are correct (I think these cars use lambda sensors not O2s actually) then the computer knows the MAF is faulty and sets a code for that and attempts to use what it knows from the other sensors to continue running as best it can. Some cars do extremely well at this (GM cars can literally run without it plugged in at all) and others shut down near instantly (BMW engines freak out and turn off if you open the oil fill port). I do not know what a 430 does.

Where am I going with all this? Well the downstream sensors (after the cats) only have one job, to check and see if the cats did their jobs and the way that is checked is by referencing the upstream values to see if for a given input of gasses into the cat if the reduction was successful or not. Some cars just have a set value they want to see everything remain below and others like the 430 are more complex on how they monitor the cats. The sensors all have to be working in order to know if the cats are fine because if one is not then the ECU will not have the ability to actually check anything.

With aftermarket cats it's complicated. Lexus and German cars have some seriously high end cats that a lot of the aftermarket stuff can't compare to. It's made worse by the fact they are also really damn sensitive to anything outside the desired value and throw codes like candy if they see anything. To make it even worse some states require EXACT part marching cats or any exhaust component to remain legal so you are totally screwed even if the aftermarket unit is good enough for the car to be happy.

If you want this fixed for good replace all sensors, replace the car battery or make certain it's good (full, deep charge that it holds without any issue) since voltage drop will make the readings way off on these cars and actually trigger canbus errors on newer ones and lead to total internal com failure, check the per bank long term fueling trims, and ohm test the MAF and make sure the PCV system and engine is sealed properly. The PCV or engine having a leak will lead to a lean code (a week and a half ago when I bought my 430 I floored it and it trigged since when I let off vacuum was high enough to draw air past the leaks and the computer saw it) and the whole system being inaccurate......not nearly as bad as a German car but enough to have an effect on these. If all that is okay and the system still says there is a "catalyst efficiency below threshold" code the yes the cat is bad and all of them likely need to be replaced.



Or alternatively just tell the computer to ignore the rear O2 sensors and cut the cats off and strait pipe it......no joke I had a customer do that to a 30k mile XK8 when I told him the price of new cats.

 

A new member with actual real world automotive knowledge = a calm sigh of releif

 

It shows the complexity I guess... I am in NY and do not know if aftermarket cats are OK. I mechanic said they never work, the other said they are fine (not talking about dealer). I did have 1 replaced AT DEALER and the other is (as of today) not replaced yet. I only hope the technicians working on my car an undertake a similar thought process. One interesting thing is that my battery is about 1.5 years old and my car EATS them. My last one I was going to replace before the 3 year mark and it died around 2+ years... but I trust / hope they would check out the battery state of health. Thanks for your input, I will have to reread it several times!

 

https://www.ebay.com/itm/Lexus-Compa...1851#vi-ilComp

 

I live in NY after market cats are fine to pass a NY state inspection any car 1996 and up cannot have any check engine lights on and can only have one "system readiness moniter" that has not cycled through.