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'96 Outback catalytic converter?


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Hi all,

I'm new to the forum. I have a question about our '96 Ouback with 122K miles. Last year it blew it's head gasket to the tune of $1700. One year later it started to smell and exhaust just like it did when it blew. Mechanic put that Subaru stopleak stuff in-no leaks. However, check light is on. Dealer read codes. Says its the cat. converter below threshold, need new radiator, and backpressure transducer valve. The car is driving beautifully. No loss of performance at all. I've done some research and sounds like the codes are not always right. The cat. converts can cost several hundreds of dollars, alone. Advice? Should we try replacing the O2 sensors first? Is there any way to tell when the cat. converters go out for real?

Thanks to all.

Carol

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Hi Carol and welcome! First, is there any way you can get the dealer to tell you exactly what code they read, like P0420 or whatever, or you could get it read at autozone, but you want the code number not just description.

 

Could just be the front and/or rear O2 sensors that need replacing; if they've never been changed then they've definitely served their life well.

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If I were you I'd reset using the "battery dance" and see if the CEL returns or if your lucky it won't at least for a while.
you need to read the thread just before yours RE: what now? sounds like you have the very common 420 code which more than a few of us have seen and nobody can agree what the proper solution is if any at all, i have it pop up all the time and my car continues to run fine and ill be darned if im gonna let a dealer take a couple grand out of my pocket for a light that keeps coming on. i just either cycle the ignition or disconnect the battery or sometimes it just goes off on its own only to pop back on a few months down the road.
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Hi Carol,

 

I can answer that for you - the "battery dance" is essentially taking power off the ECM by pulling the battery cable off the negative terminal. Then let it set for a while with the battery disconnected -- it usually takes a few minutes for the memory in the ECM to be reset that way. I can't remember what Subaru says, but if you leave it off for a half hour I think that is sufficient to make sure that the codes are all cleared.

 

Then, once you reconnect the battery, you will be driving with a "clean" ECM, with no codes set. Essentially the car will be trained by you, given your driving style. And if you are lucky, and those codes were set only as a result of some transient that happened but is now gone, you will be able to drive around without spending any $$ on unneeded repairs.

 

If you're not lucky, those codes will come back. Then as someone else here said, you should get the actual codes read by someone at an Autozone or similar place, and then post those numeric code numbers here. We can help you more at that point.

 

One little idiosyncracy with these vehicles -- oftentimes the P0420 code, Cat below threshold, isn't really a bad Cat -- it can be caused by a weak O2 sensor (usually the rear one). So, if you get another P0420 after clearing all the codes, then we'd recommend trying a replacement of the O2 sensors before you go thru the trouble and expense of getting new Cats.

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also doesn't hurt to check the wire connections to the o2 sensors.

 

Hi Carol,

 

I can answer that for you - the "battery dance" is essentially taking power off the ECM by pulling the battery cable off the negative terminal. Then let it set for a while with the battery disconnected -- it usually takes a few minutes for the memory in the ECM to be reset that way. I can't remember what Subaru says, but if you leave it off for a half hour I think that is sufficient to make sure that the codes are all cleared.

 

Then, once you reconnect the battery, you will be driving with a "clean" ECM, with no codes set. Essentially the car will be trained by you, given your driving style. And if you are lucky, and those codes were set only as a result of some transient that happened but is now gone, you will be able to drive around without spending any $$ on unneeded repairs.

 

If you're not lucky, those codes will come back. Then as someone else here said, you should get the actual codes read by someone at an Autozone or similar place, and then post those numeric code numbers here. We can help you more at that point.

 

One little idiosyncracy with these vehicles -- oftentimes the P0420 code, Cat below threshold, isn't really a bad Cat -- it can be caused by a weak O2 sensor (usually the rear one). So, if you get another P0420 after clearing all the codes, then we'd recommend trying a replacement of the O2 sensors before you go thru the trouble and expense of getting new Cats.

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Wow. Y'all rock. I've been researching this stuff to death in the last few days and I really appreciate your feedback. I think we may go with the dance first then a rear O2 sensor if needed. I'm sure they are originals and the issue with the exhaust/blown head may have hastened their demise. I'll keep you post.

Thanks so much.

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Look at it this way. If you need a new cat, odds are you should replace the front o2 sensor anyway. Since the front sensor is cheaper then the cat, replace it with a GENUINE SUBARU O2 sensor and see what happens.

The radiator should have been cleaned out when they did the HG for that price, shame on them if they didnt do it. If you have no complaints about it running hot dont worry about that.

All subarus it seems have that smell to some degree. The brand new outback i rented had it also, and the service writer said they couldnt find it.

What the heck is a backpressure transducer valve.

 

nipper

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Part of the EGR circuit in some designs. Didn't know that it was part of the Subie system, though....

 

<added later> Yup! It is part of my '96 OB -- it's there right above the EGR valve.

 

ah ok now i know what it is.

 

Have an autozone read the codes and tell us what they are so we can tell you if its a valid code or not.

 

nipper

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