Check Engine: catalytic converter

[Lotek]

So, theres probably a thread about this already, but i couldnt find it. my check engine light goes on and off constantly, although its on more often than its off. i barely squeezed by inspection, but luckily i knew the guy so he got me by. im told thats its something with the cat, not sure exactly what. do i need a new cat? ive gotten the codes reset, but after a few hundred miles it just comes back on.

[Platinum_Racing]

It could be one of probably two things.

 

1) You need a new cat. Generally if a cat is clogged it will reduce power output by increasing backpressure substantially. Sometimes to the point of overheating and blowing exhaust gaskets, causing exhaust leaks. You can usually tell if the cat is bad if the vehicle runs noticeably better with the cat unbolted, or if the temperatures on the inlet pipe of the car are considerably higher than the temperatures on the outlet pipe of the cat.

 

2) The second O2 sensor located behind the cat is on its last legs, and is sending misinformation to the ECU. This is unlikely because the second O2 sensor has its own codes for when it dies. It has an overvoltage code and an undervoltage code that it throws when the values it sends to the ECU become increasingly out of spec.

[Lotek]

thanks. ill probably end up buying a new cat, probably stock idk. maybe ill have to pick up some borla replica headers with that

[cman7]

I'm not sure I know a single older subaru that doesn't suffer from this problem. Mine goes on and off as it pleases.

 

This CEL code is common with HFC's.

[httrdd]

Mine had not done this yet! (Knock on wood!) I would just hammer the cat out and there you have a high flow cat.

[SLegacy99]

Another possibility.

 

When was the last time that you had a fuel filter done. This wouldn't trigger a CEL, but if it's been awhile, replacing it should help you pass emissions. Not a guarentee though.

[AKLandcruiser]

I just purchased a 97 EJ22 Legacy L with 150K on the cheap due to the fact that the check engine light comes on every now and then due to the catalytic converter according to the previous owner. I verified this with a reader from the local parts store but it didn't shoot out a code, the CAT symbol was blinking on the readout and the yellow light on the g/y/r emissions led's lit up.

 

My question is how can I narrow it down to maybe just a sensor and if the converter/converters? need to be replaced is this something I can do myself so I can pass emissions? An impressive collection of service records accompanied the car including a recent timing belt, top end rebuild, so I'd like to get this nailed down so I can take it cross country.

[Stang70Fastback]

Out of curiosity, what is the average life of a cat? This car is quite a few years old AFAIK the cat has never been replaced. It runs OK right now, but it's definitely not purring like it did when it was new. I have no issues or indications that the cat could be clogged, etc... but with this many years on it, is it pretty much a guarantee that a new cat would likely be a worthwhile investment? Or is it also just as possible that the cat is perfectly fine? I know cats can live for 15-20 years, but I would assume that cats on cars, exposed to harmful chemicals, have a significantly shorter lifespan.

 

/serious question.

[AKLandcruiser]

Anyone? Is there a bolt-on replacement caty for these? I'm going to crawl under the car today and change the ATF fluid and transmission filter so I'll scope it out but I wanted an idea on which aftermarket brand to buy.