Replacing catalytic converter on my 2011 outback

Heard a funny intermittent rattle and my mechanic told me that my check engine light should be going on any time now as my cat converter is bad. The part is about a thousand bucks! Looked on line and see some aftermarket ones from walker and some other retailers. I live in VA. Can anyone tell me if it is worth buying an aftermarket one and saving the 500 bucks? Ps, my car has 103K miles on it,.

This can be sort of a crap shoot as to whether the aftermarket model will work as well as the OEM part. I have seen instances (all of them with Toyotas, I believe) where the aftermarket cats caused the CEL to light up even though everything seemed to be working properly. However, you might luck-out with the aftermarket part.

Overall, what would concern me about this issue is that your cat went bad after just 4 years and ~100k miles. Normally, these components last at least until 200k miles–unless there are “issues” with the engine and its fuel system. Are you sure that there are no issues with the engine or its fuel system?

I am going to take it to the Subaru dealer for an evaluation. The guy who told me it is bad did not hook it up to a computer I think. I do not think I have any other issues, The car has been great. I service the vehicle according to factory recommendations and have all the big services done at the dealer. I had the big 90K one done and it included changing the fluid in the CVT. Thanks!

A 2011 model is a little young for a converter failure. Seeing as how a rattle is involved I would strongly suggest the exhaust heat shields be checked.

In the event this is a heat shield rattle (far more common) those can often be solved by tacking a weld here and there or even simply inserting a few sheet metal screws through the heat shield until it bottoms out.

Once back in the 80s there was a rash of Subaru heat shield rattles and the Technical Service Bulletin from Subaru stated just that; drill a couple of small holes and insert a few screws until they bottom out. This dampened the heat shield and as hokey as it sounds it works. Five minutes, 5 cents worth of screws, and done.


There is a chance the monolith inside the catalytic converter has broken free of the shell, and is just rattling around in there

In many cases, it does cause a P0420 low catalytic converter efficiency fault code, which would result in a check engine light

I’m not a Subaru expert, but I’ve seen this type of failure very often on other brands. Very expensive cars, low miles, and only a few years old, like yours

it can happen

Drive the car for several minutes, until you hear the rattle at idle. Go to the shop. Have the mechanic rack the car. Then have inspect the heat shields. If they’re not loose, have him tap on the cat(s) with a rubber mallet. In about 5 seconds, you’ll have your answer

The state I’m located in, the cats with the loose monoliths were replaced at no cost to the customer, as long as the car was within 7/70 emissions warranty period.

To expand on what db4690 said, you probably have an emissions warranty for a longer period than the regular warranty. I don’t know if 7/70 is correct, but make sure you check the details on yours before you pay for anything.

It is 80K, I checked with Subaru

First check for a loose heat shield as ok4550 said. Heat shield rattle is a common problem and easily (and cheaply) fixed.

Hi all and thank you so much for the advice. This board is amazing and this was my first time here. I took it to the dealer. They said indeed it is a loose heat shield but because of the complicated construction of the cat converter, the only way to fix the rattle is to replace the cat. He basically said,” if the occasional rattle doesn’t bother you, I’d leave it alone” So, that is what I am doing, I am leaving it be until there is a real problem.

Remember, however, that dealerships normally only replace parts, and don’t do repairs to existing parts. If this is indeed just a loose heat shield, any honest mechanic (or muffler shop) can secure the loose heat shield with a hose clamp or other extremely cheap part.


With all due respect, do NOT “leave it alone”

You have a legitimate complaint, which the dealer verified

I am assuming that the catalytic converter would be replaced at no cost to you, if you had the dealer perform the repair

Because the catalytic converter usually falls under 7/70 or 8/80 emissions warranty

In a few years . . . when you don’t have either new car or emissions warranty . . . and the noise is REALLY bothering you, things will get ugly. Because a high quality cat from the dealer is very expensive. And a mediocre aftermarket cat costs less, but is a compromise. I won’t get into the details concerning the compromises at this time

Go back to the dealer and insist that they replace the catalytic converter now, at no cost to you. If need be, talk to the same guy that verified your complaint

I would not tolerate that kind of noise, if it was my car. Especially considering the repair wouldn’t cost you anything

If no happiness, take it to a muffler bender guy, mine welded a split converter for $15, a spot weld could be done.

He has 103k, so out of warranty.


I forgot that part . . . and it changes everything

Wow, that’s a LOT of driving

@db4690, the car has 103,000 miles on it. I’m not sure it still qualifies for warranty replacement.

Wow, that’s a LOT of driving

I have a customer with a 2010 CRV. Last time it was in I noticed that the Bridgestone tires we put on last year sure aren’t lasting. They were down to 4/32" tread.

Then I saw the car has 192,000 miles on it and the tires have over 50,000 miles on them.

The heat shield is there to save your car from burning up. Without it, if you park on dry grass it could catch fire. Also, keeps excess heat off the floor of your car. Emissions warranty will cover it.

Nope, it’s out of warranty.