to all of you with cat converter problems, what kind of driving do you do?
Mainly highway driving or city driving?

The reason I asked this is because I have come across a LOT of lexus drivers with their cats going bad... I have read from a lot of members that Cat converters arent supposed to go bad and should last the life of the car.

MY cat converter went bad 2 weeks ago and my friend with a 99 LS400 cat went 1 week later literally.
My father's cat on his 97 LS400 went bad several months ago.
And a lot of guys with dual exhaust lexus' that go to my mechanic have failed cat's

So do you guys think its the city driving that caused this? Or just mere coincidence?

By the way a suggestion for a proven good working replacement cat converter would be appreciated, not only for me, but for a boatload of guys that cant afford the 1500 price tag at the moment

 

I used to have IS300, which I sold about a year ago and then few days later buyer had called me that he had to replace one of the CATs on exhaust manifold! Car had only 86k miles and it was always well maintained and etc. Majority of miles were freeway.
I believe it's the quality issue.

 

anyone else with any experiences?

 

The secondary cat was replaced on mine at approximately 95K miles by the first owner.

 

My cats are bad because I get a methane smell if I get on it hard but if I dont then I dont smell it. My car doesnt pop a code for cats though. I doubt that city is the problem because my cats have had the issue since I bought the car and it was originally a cali car. Dont know what the reason is.

 

Cat are supposed to last the life of an America car(I keed, I keed ), Japanese cars tend to last a little longer. Most cats have a designed lifespan of around 100-150k miles depending on the manufacturer. It's a wear and tear part like any other in the car. Also, many people consider a car's useful lifetime to be around 10-15years. Many people in the US trade in their cars once they are only 4-5yrs old. So, by that logic of 10-15year old lifespan...yes the cats did last the life of the car

Hypothetical "vehicle life" aside, a possible cause of older Lexus having failing cats is due to worn out motor mounts. This allows excess vibration and movement of the engine. The cats are fragile and it is best to disturb them as little as possible. The super smooth and dampened Lexus mounts tend to need replacing at around 80-100k miles. Once they are worn, they lose the ability to dampen all the vibration, and those vibrations will dissipate through the car body and exhaust system.

One final note, make sure that your car is really dead before replacing it. Many times a faulty O2 sensor can trigger a catalytic converter deficiency. Many people have brought their cars to me to check out their check engine lights. I would say 60-70% of the time, the faulty cat code is actually triggered by a faulty O2 sensor!

EDIT: Also on that note of a faulty O2 sensor triggering a bad catalytic converter code. I know there are some shops out there that just replaced the sensors and charged the customer the $1000-1500 for the replacement cats, but never actually replaced the cats! Shady stuff.

For those of you guys that really have a bad catalytic converter, look around for aftermarket cats. Buy the one that is certified for use in California because their emission standard is higher than the other states. If you buy the cheap-o 49 state(sans CA) legal cat, then those have less catalyzing material in the converter. This lowers the cost, but the converter efficiency may not be sufficient to pass emissions testing in your area. FYI: The factory Lexus converter is CA certified.

 

When do you know the mounts need replacing?

 

Usually it's according to mileage and age. The mounts are made of rubber, so it will naturally wear out and harden over time. A good time to replace them is either 6-7 years or around 80-100k miles/130-160k KM for you metric guys

 

Thanks for the quick reply. My GS3 just passed 160k km so I guess I should replace them.

On my ex Prelude, the mounts would tear apart and you would know when to replace them when you start hearing a metal-to-metal sound as the engine moves.

 

Keep in mind. The mounts will still be in one piece after that many years and miles. You might take them out and wonder why the hell you just replaced them, but the difference is inside the mount. The dampening material wears out over time and does not do its job as well.

 

Thanks, appreciate the help.

 

Good to know.

 

Has anyone found a good aftermarket CAT that this legal in California? OEM is way too expensive!

 

Best to look around junkyard or forums. You can find a used cat for around $100-150 or so. It uses the same one as the IS300 as well, so you can search for the cats for that car instead for more results. Also, the cats cost so much because they come welded onto the exhaust header on the car.

 

IN CA you cannot buy a used cat from a junkyard at least...