Rep Power: 0

I'm throwing the code p0420 "catalyst conversion running below threshold" which I took as simply it's clogged, but I just had the cam shafts sensor replaced and i think maybe too much fuel got down the exhaust with the multiple misfires and fouled the sensor. I drove on it for maybe 30 miles after the light came on with a some serious chugging, a pull over after I got a heavy sulfur smell and misfires on the way to the mechanic. Anyone know? I pulled both sensors and they are obviously old, but could they be the problem?


Thanks guys!

 
Rep Power: 186

How do you know you had multiple misfires? Were you throwing that code before?

As ezone has said in multiple posts, misfires can kill a cat in a matter of minutes. You drove it 30 miles. It very well could be dead. Hopefully ezone will chime in on this one and say the same or offer better advice.

 
Rep Power: 517

The definition of code P0420 is not "a sensor".

A quick glance showed me about 16 different codes that cover O2 sensors (2005).
But only one code for a cat.

 
Rep Power: 0

I only got the pop pop noise the last time I drove it which was from my friends house to my mechanic. It was only throwing the cam sensor code before all this.

 
Rep Power: 0

Right, i looked up the code and the fixes, but I was hoping that maybe the sensor just got dirty and it thinks the cat isn't working...

 
Rep Power: 517

There's codes to cover most sensor failures. Very few sensor failures escape the computer.

There are ways to cheat the system.


A few CAT scenarios:

(GUESS)
You might find 75% of people saying they replaced O2 sensors for the cat code. (I have even witnessed "professional" techs, at a dealer no less, do the same. SMDH)
Because, cheaper? (Or ignorance, whichever.)

(Cheapo sensors that the computer doesn't like just creates more headaches and can mask the true problems.)

What you won't see is 2/3 of those updating their posts saying the sensors didn't fix it and they had to get a cat anyway.
Because, ego?

Of those, you might find that more than half got cheapo discount cats that didn't last long enough to get out of warranty.
Because, cheap.

And that warranty only covers the cheapo cat, not installation and incidentals.
Because, fine print.

So they are out the cost of installation for every warranty replacement, which might be as much as a cheapo cat itself every time.

What is the cost of that cheap price now?

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Or, they believe the cat code and just go get a cheapo cat, but just can't believe their car still sets a cat code soon right away next week. (New cat just CAN'T be bad, right?)
So now they go replace all sorts of sensors and every other gimmick/snake oil/trick they can find on the internet (or the shelves at DangerZone), to no avail.

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Or maybe they get a cat but don't actually fix the ROOT CAUSE of the cat failure. I've seen this more than once. Even from dealer techs. MULTIPLE new cats ruined.

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I have witnessed an exhaust shop install a cheapo cat on the wrong bank (V8 GM truck), multiple times. Not only did they cut off an OE cat that was still good, they replaced it with something cheap that failed within a week. Twice.
Then finally replaced the actual bad OE cat with another cheapo cat. Now it has 2 cheapo cats that the computer hates. Codes will not stay away, and the customer just can't understand and hates everyone involved.
Customer is out of money now, and a single correct factory cat would have been about the same price as what this guy spent at the exhaust shop.
(Diag done by me, customer didn't like the price to fix, went cheap and got their moneys' worth. Rechecked diag several times throughout this process.)

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In spite of the horror stories, we actually DO have some customers with aftermarket cats that have been working for a long time. They are out there, and they are not the cheapest cats on the market.

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I've got more stories--- and carpal tunnel syndrome from typing.

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/Wait for next victim with a cat code.
//Lather, rinse, repeat. Wipe hands on pants.


///Sunday morning bored

 
Rep Power: 517

A cat code is never defined as "clogged".

 
Rep Power: 0

Alright my friend so what would you recommend? I have virtually no budget, need the car to last a while, wouldn't mind upgrading exhaust, but probably at a later time. I'm 19 currently the only one bringing money into the house because my mom lost her job because of medical reasons, and I just had to pay 300 toward a new sensor and battery, that I didn't have, plus I just got done with a bs $900 VA speeding ticket, and now this is popping up. I'm just trying not to make a hasty decision. I was hoping maybe it would simply be a sensor messed up and I needed to fix it. I mean what really are my options? I'm not gonna cut it clean out, I'm not running anything illegal.

 
Rep Power: 186

It sounds like he's saying two things:

1. You need to figure what caused the cat to fail.

2. You need a new cat, OEM preferred.

Correct me if I'm wrong ezone.

 
Rep Power: 517

Yeah, pretty much that.

I think he already has a good idea of what killed the cat.
As long as the engine is fixed now and runs good again and the computer has good control of fuel, a replacement cat should be ok whenever the time comes.

A cat code by itself is not going to stop the car from running.
As long as the cat is not clogged and has not broken apart to possibly clog up the exhaust (THAT would stop you from going places), you can probably drive it as-is until money frees up or an emissions test comes up (if you have to do that)..

Hell, if it does clog up you already knew it was a possibility, you could be stranded or really slow to get home.

If you do choose to ignore it for now, the Check Money Light will be on all the time, and you might never know if a new problem pops up unless it makes the car run bad enough to notice.

 
Rep Power: 517

I guess the point to my long drawn out post was don't waste money on sensors it doesn't need, and don't waste coin on a cheap cat the computer won't like..
If it needs a cat, it needs a cat. Save your money and do it right, don't get the cheapest thing available because you don't have any money.

If you go aftermarket, get a cat that is California CARB approved, they are much better than 49 state cats. California emissions standards are more stringent and AFAIK the warranty is better on the cats built for there (5 year warranty IIRC).

 
Rep Power: 0

Yes, the likely culprit was the cam sensor and the misfires putting too much fuel down the exhaust. I tried simply running bg44k through the system, a friend said it fixed his daughters cat, but that didn't help this, although it seemed to have cleaned everything else well. My little girl like to go!

Ezone, what do you think about dropping the exhaust off one from a junk yard? I know it could be a crap shoot, but my cat has heat welded to the back system. An alternative I was also thinking about was getting a weld in one, not a cheapo, that I could have put in. I have this sickening feeling if I got to my mechanic he will quote me a grand for parts and labor. Not that i don't trust him, I just think a muffler shop would be more appropriate?

Also wanna say thanks. I truly appreciate the input.

 
Rep Power: 517

Do you have an EX or what? Where is the cat?

Sure, junkyard is an option IF they will sell you one. But, it's used and all. You really don't know anything about its past.

Craigslist?

 
Rep Power: 0

Yeah, it's an 04 ex with mid exhaust cat. My yard will but yeah it would be used. I don't know if I could find one on there. I found just the cat on ebay for like 130, but I don't know if it would line up right and I would need the whole thing from the cat back since mine is heat welded together. What if I went with a Magnaflow cat and then the stock pipes back? Is Magnaflow gonna last me like stock will? They have a mid exhaust cat like the one I have so it would just bolt up.

 
Rep Power: 517

If you need it to last, then please refer to this post

If it was my own car, I'd probably prefer a used OE cat with low mileage than aftermarket.

 
Rep Power: 0

Would you trust ebay or Craigslist? Like fitment? My brother said he had alot of friends buy exhausts of ebay and they wouldn't line up.

 
Rep Power: 517

I can't even answer that.
I deal with OE, and that's pretty much it.
OE fits right and works right.

I was thinking check CL for someone parting out an identical Civic, grab a stock cat and pipe assembly with the O2 sensor and all..


I can't afford to screw with crap that ALMOST fits or ALMOST works when it comes to customers and their cars. I make my money on time, and dicking with stuff that doesn't quite work just eats up a ton of time. I can't afford it. (Autozone et al., I'm looking at YOU!)


If I need custom stuff, I know there is fabrication going into it and try to plan accordingly. Hard to plan that way though, you never really know what all you need to make something work.

Custom exhaust? I go (or send) directly to the exhaust shop, they have the stuff to handle it. Had to do that for my truck since the rear axle gets in the way of any pre-made exhaust one can buy at a parts store. They did in under an hour what might have taken me a whole day, even if I had the materials and equipment at my disposal.