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-   -   Check Engine says Cat is clogged. Test Pipe? (http://legacygt.com/forums/showthread.php?t=201119)

phantommaggot 02-05-2013 12:17 PM

Check Engine says Cat is clogged. Test Pipe?
 
Hi,

So I'm driving in some pretty snowy weather last weekend. My check engine light comes on. My car smells like gas. I go directly to the local autozone and they say the code is 'clogged cat causing high air/fuel mix'

So, I want to assume that since it is overfueling my car it is probably the cat near the 02 sensor. Is there a high flow cat I can get to just bolt in and replace it? possibly a test pipe? I searched but I only get WRX downpipes, 2.5turbo legacy downpipes ETC.

SCASEYS 02-05-2013 12:43 PM

was code PO420?

phantommaggot 02-05-2013 02:14 PM

That is something I do not know.
I just saw the readout where it said a/f ratio and catalytic converter.

subikid90 02-05-2013 03:16 PM

http://legacygt.com/forums/showthrea...pe-198385.html

compsurge 02-05-2013 03:29 PM

Don't get a test pipe.

Find out the actual code (Pxxx) and report back. Something else could be at fault here. Catalytic converters don't go bad all of a sudden. You said it smells like fuel, maybe you have a failed injector that dumped fuel into the exhaust.

phantommaggot 02-05-2013 04:58 PM

Alright, I'll go get it checked again tomorrow afternoon. See if they can give me the number.

Its also idling really high on start up at random. Like 1300-1800 rpm.

Thanks guys.

firebox40dash5 02-05-2013 06:15 PM

No code exists that says 'clogged cat causing high air/fuel mix'.

A melted/clogged cat will generally make the car run like crap... low power, missing all over the place, etc. If it's a P0420, your cat could indeed be done for, even if it's not clogged, or it could be as simple as the rear O2 sensor. If it smells like raw gas, it's possible there's a problem with your front O2 sensor and/or its wiring that's making the car think it's running lean, even when it's rich as hell. That'll usually be acommpanied by a code for the front O2 sensor and a lean mixture code.

phantommaggot 02-06-2013 06:34 PM

Autozone Printout reads as...

p0420
catalyst efficiency below threshold bank 1 probable cause.

1- rich a/f ratio
2- Ignition system malfunction
3- Faulty catalytic converter

octain11 02-06-2013 06:54 PM

It is not necessarily your cat, it can be a bad O2 sensor,before purchasing a new cat, get a new O2 sensor swap it out, reset the ecu, if it is not the 02 the CEL should light up again around 50 miles.

phantommaggot 02-06-2013 08:28 PM

Just pull the neg terminal to reset the ECU?

octain11 02-06-2013 08:38 PM

yessir

firebox40dash5 02-06-2013 08:39 PM

You can disconnect the battery or pull the ECU fuse to "clear" the codes. It's possible it'll come right back, or it might not. Sometimes you just get a "flyer" outside of the parameters that'll set off a P0420 every once in a while, sometimes there's a real, constant problem, whether it's a cat that's truly no longer efficient, a bad rear O2 sensor telling the ECU the cat is messed up, or something causing it to run rich all the time. Honestly, without a way to watch the outputs of the front and rear O2 sensors, it's about impossible to pinpoint which one of those it is.

I generally recommend a new (quality, meaning Denso or NTK, IMO) rear O2 sensor. They're rarely over $100, and usually are the cause of a P0420 on a car that's otherwise running right.

compsurge 02-06-2013 10:07 PM

Check Amazon or rockauto.com for the best deal and rent the tool from AutoZone if you don't have it already.

phantommaggot 02-07-2013 07:12 AM

Quote:

Originally Posted by firebox40dash5 (Post 4282197)
You can disconnect the battery or pull the ECU fuse to "clear" the codes. It's possible it'll come right back, or it might not. Sometimes you just get a "flyer" outside of the parameters that'll set off a P0420 every once in a while, sometimes there's a real, constant problem, whether it's a cat that's truly no longer efficient, a bad rear O2 sensor telling the ECU the cat is messed up, or something causing it to run rich all the time. Honestly, without a way to watch the outputs of the front and rear O2 sensors, it's about impossible to pinpoint which one of those it is.

I generally recommend a new (quality, meaning Denso or NTK, IMO) rear O2 sensor. They're rarely over $100, and usually are the cause of a P0420 on a car that's otherwise running right.

I usually do go with a brand name on parts.

Would rear 02 sensor be causing the gas usage and smell?

compsurge 02-07-2013 12:56 PM

If the O2 is malfunctioning, the car could run rich to help reduce possibility of damage due to improper fuel metering. It should be anywhere from $30-60. Check Rock Auto out.


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