02, cats, P0420, and expensive Mechanic Diagnosis

[Skydoor]

The Check engine light came on about a year ago, on my 96 Subaru Outback 2.2l a mechanic said it was the rear O2 sensor and that it was probably just the sensor, which can act up. I decided not to spend the $200, to fix it.

Two weeks agoI brought my car to a mechanic I had never used before to fix an unrelated problem, he said the codes said both front and rear 02 sensor, and that they needed to be replaced, and that the system should be flushed (Intake, injectors and catalytic system). I reluctantly agreed. Two weeks, car was fine, now the engine light is on again, reading the same code as before the work was done (P0420) catalysic effiency bank.

Mechanic spent about $500 fixing the two o2 sensors now says it will be $630 to replace both cats (front and rear). He did agree to knock off $65 for the time it spent replacing the 02sensors. This seems like a very expensive way to diagnose a problem. It seems like the o2 sensors were fine in the first place. Is this standard protocol? Should the mechanic be held accountable in any way?

I have found a cheaper mechanic who will install parts I find online, I found a company Catco which sells direct fit subaru cats, for half price, anyone have any experience with them?

[tune-a-fish]

It sounds to me as though your ox sensors were working properly "signaling a cat failure".

My question would be did this shop do a exhaust flow test before determining the sensor failure?

As for the after mkt. cats just google the manufacturers customer comments?

Edit: here is the company link http://www.catco-converter.com/

[nipper]

What brand O2 sensor did he use for the front one? It needs to be OE. Also i never heard of a cat flush before.


You may need a cat, i'm just not convinced yet. Whatever you do keep away from eastern catsalytic converters.
nipper

[methius]

I had the same code when my Knock Sensor was bad. I replaced it, and the code went away.

I also had a mechanic tell me to replace the whole system (to the tune of about $1700). I voted no on that one!

the knock sensor was $60 bucks and took about 10 minutes to install myself.

My best suggestion, is take it to AutoZone or someplace with an OBDII code reader and stand there while they take the codes. Then write them down and look them up here. That will tell you what NEEDS to be replaced.

[xnavnuc]

You, my friend, have been 'Easter Egged' by the mechanic. Some of the jerks that are out there just don't have a clue as to the function of the sensors and the Cats.

When we had to replace cats we always used OEM (Subaru). I used to sell used cats to a scrapper and he would never give me more than 1/3 of what a Subaru cat would fetch for ANY Aftermarket unit. You get what you pay for and Platinum and Iridium ain't cheap bucko.

You might scrounge around a local wrecking yard and have them sell you a complete exhaust system from a similar model/year and then throw away everything but the cats (provided the flanges aren't badly rusted).

Nudge nudge, wink wink.

[Skydoor]

Well thanks for the info, I am not sure what to do right now, will probably bring it to another mechanic to have a second opinion. A friend of mine had the same series of problems CEL, o2 sensors (actually the same mechanic) then CEL again, so she had the cats done... welll guess what, CEL on again. So either the whole system is junk, the CPU is off or there is some other small problem that mechanics aren't looking for.

We'll see... I just don't want to drive it and mess up the 02 sensors which are new, or catually have a bad cat and be polluting any more that I am already.

[xnavnuc]

Search around on this site and I'm SURE you'll find plenty of info that will help you. My philosophy is kind of the 'old Mainahs, do what ya can to get by.

[nipper]

Originally posted by Skydoor
Well thanks for the info, I am not sure what to do right now, will probably bring it to another mechanic to have a second opinion. A friend of mine had the same series of problems CEL, o2 sensors (actually the same mechanic) then CEL again, so she had the cats done... welll guess what, CEL on again. So either the whole system is junk, the CPU is off or there is some other small problem that mechanics aren't looking for.

We'll see... I just don't want to drive it and mess up the 02 sensors which are new, or catually have a bad cat and be polluting any more that I am already.

I repeat my question, what brand of O2 sensor and cats did he use?

I bet its cheap aftermarket o2 sensors.

nipper

[Skydoor]

Not sure what type of O2, is there a way that I can check, or do I have to find out from him? Cats have not been done yet.

[nipper]

How much did he charge you for the part? And yes you can always ask him.


I think your problem (and your friends) is just bad parts, not bad cats.

nipper