Rep Power: 0

The previous owner had a CAI that I recently returned to stock. When I was installing the air cleaner box on top of the throttle body, I was having a lot of trouble getting it to sit properly (couldn't get the rubber throttle body to plug onto the bottom of the box). I ended up cracking a small piece off of the bottom plastic cylinder-shaped piece that plugs onto the throttle body and have been getting CEL lights periodically that will stay off for a little while and then come on again. I finally got a chance to read them today and had P0133, and P0420. Are these directly related to the improper seal between the throttle body and the bottom of the air cleaner box? I remember I did have a P0133 along with a p1457 a few months back, when I replaced the canister vent shut valve (which did end up fixing the problem of the p1457, and I didn't get another CEL until this replacement). My other thoughts are that he may have flashed the computer to get the CAI not to throw a code, and now that it is stock again, it's throwing codes. Any ideas?

 
Rep Power: 0

I should mention too that the exhaust header is aftermarket, and the exhaust is a bit loud, may have a leak in the back. The car was a police repossession which they used for surveillance so it probably spent a good deal of time idling. Has 76,000 miles, and I think the police owned it since about 44,000. Is my problem here really just an exhaust issue?

 
Rep Power: 518

Did you google the codes?
Is this an EX or LX?
P0133 is an O2 sensor. Front sensor, slow response. You say you have a header, what kind? Got a pic?
Where is the front O2 sensor mounted? I mean is it in the collector or is it in one pipe from a single cylinder? Got a pic?

P0420 is the catalytic converter. You say you have a header, does the car still have a cat? Exhaust leaks can cause false cat codes to set sometimes.
See if the cat is missing.

The cat code had to set prior to the O2 sensor code setting. (The O2 sensor code prohibits the cat monitor from running.)

See if the cat is missing.

If it was a normal unmolested car, I'd say to start with the O2 sensor and use a correct DENSO (or NTK?) unit. (See what brand is in it now when you remove it. I think it should be DENSO.)
Fix any exhaust leaks between the engine and the cat. The exhaust should be tight and leak free all the way to at least 2 feet past the cat if the cat is under the floor.

See if the cat code comes back later. Then address that.

 
Rep Power: 0

Thanks for your help. I took it into the dealer today to top off the coolant after I'd had the timing belt done a couple weeks ago. I mentioned how I'd gotten these codes and we looked under the car. Sure enough, no catalytic convertor. How much am I looking at to replace it? He was saying $800-1000, I'm assuming those were Honda dealer prices. He also said that I might have to do the pipe behind it, and that aftermarket cats can still throw a code and that I might have to try a couple different ones to match the specific tolerances of the OEM. It is the EX model. Does the header have to come off as well? It looks like it's a DC Sports brand. The technician said that it was a ceramic header.

 
Rep Power: 518

Aftermarket parts are cheap for a reason. They usually can't make the computer happy for very long.

Dealer cats are not cheap, and they are not cheap for a dang good reason. They WORK.

The only non-factory choice I would even consider is a California C.A.R.B. approved replacement cat.

And their guess at the price is a little low.

(I looked up a 2 door car for this)
......
The cat retails for almost $1100.00 USD.
Add maybe $150 for shields, gaskets, nuts and bolts, etc.
Add maybe $100 for installation ONLY IF it is still an original configuration.
Meaning: If the front and rear pipes no longer allow the replacement cat to be BOLTED in place as per original design, then you will be buying even more parts until it CAN be bolted in as originally designed. Add more $$$.$$

The Honda dealer SHOULD have given you a complete proper estimate for the cat job, IMO


You still need the front O2 sensor? That's another ~~$90- plus installation.
I'd still want to see the design of the header and sensor placement before I'd say it will work.


If the engine doesn't run RIGHT, you can ruin a new cat in a hurry too. Keep that in mind.

 
Rep Power: 210

replace the entire exhaust.....header and cat with OEM

after the cat you can go aftermarket if you want

this is why you shouldnt buy a car that some joe weekend mechanic has been building in his backyard

 
Rep Power: 235

Assuming it's an EX as you were looking under the car, the parts are a little cheaper at the online dealers: http://www.hondapartscheap.com/parts...t-pipe-muffler

If it has an aftermarket header as well you may have to replace that too. The good news is the header is only $135: http://www.hondapartscheap.com/parts...fold-sohc-vtec

And, if you want it to run right and pass emissions for years to come use an OEM cat and DENSO or NGK O2 sensors only.

 
Rep Power: 210

i was assuming the OP lives somewhere where emmission tests are not required....he would have had to have the test done and pass it to transfer the ownership.....and it would never pass without a cat

 
Rep Power: 235

Really? You don't have to do that here. What state are you in?

 
Rep Power: 210

im in canada....

anytime ownership is changed here a vehicle needs emmissions test done....and after that every 2 years....i believe this only applies if you live in a major city though....if you live way out in hickville you dont need to do emmissions at all....

 
Rep Power: 0

I actually got the car from a police auction, was a repossession and they had been using it for surveillance for the past few years. So I was pretty surprised that they had been driving it with no cat, but I guess they can do what they want. They light has been off for a little while now, probably 30-40 miles. Is there any way it could have passed the emissions test without the cat? I did have it inspected recently, but I'm assuming they just didn't do a proper inspection. Is it possible to flash the computer so that it will override the codes? Not that I intend to, I'm just wondering if the previous owner might have messed around with that, and if I'll have computer issues if I change out the exhaust and add in an OEM cat. Do I have to go to the dealer to get OEM parts, or could you get them from a Mavis type place as well?

 
Rep Power: 518

It's possible to drive for a long time without ever getting the self tests to run.

The computer only tests the cat under a set of very specific driving conditions, and only runs the test once per drive cycle if it does run.

The computer stores the results of 6 tests, then compares the averages to a preprogrammed threshold.

Then it has to fail that test (average result below threshold) twice in a row before it turns the light on.
Inspected by whom?

Doesn't really matter now.

Not without going to an aftermarket control unit AFAIK, but it is possible to fake the sensor readings using a couple of common methods to fool the computer.

But if the car had those installed, you shouldn't have ever seen any cat code. Right?

 
Rep Power: 0

Ok makes sense.

So if I go to Mavis or one of those places and have them replace the exhaust components before and including the cat (and possibly the pipes after if they didn't match up), I'm very likely to still have issues with CELs? I'm pretty much stuck going to the dealer and paying for OEM parts? Is this specific to Hondas, where using a non-OEM cat will throw codes, or is that the case with most cars? Seems like these muffler places would get a lot of complaints.

 
Rep Power: 518

Maybe. General rule of thumb is "sooner, rather than later" when using non-factory cats.

My advice comes from nearly 2 decades of experience with OBD2, several different auto manufacturers.
I'm here to FIX cars, not "work on cars". There IS a difference.

I will turn away someone wanting a cheapo aftermarket cat. I don't need that headache in my bay.
You can be mad at someone else when your cheapo cat is bad again, not me.






Mind you, some actually DO last a fairly long time....but far too many just don't last. You can't tell ahead of time what will happen, in most cases.
Mail order?

It's pretty universal. You get what you pay for.

The self testing done by the PCM is far more stringent than tests done at an emissions test station.

Do you REALLY think they will tell you if they did?
A good percentage of them make it past the warranty period, and they make money on those.
The rest don't make it through the warranty, and they lose unless they lie.


Original cat was warranted for 8 years/80k miles, (unless it was in California, might be 10/150k there).

Cheapo replacement MIGHT have a 12 month/12k mile warranty, if you are lucky.

Calif. certified replacement cat has 5 year/50k IIRC.

If any of them go to crap under warranty, you still pay labor to replace it every time (except factory, if it is within the warranty period).




Think about this: "What is the COST of that cheap PRICE?"

 
Rep Power: 0

Will many places allow you to bring your own parts and have them put on? I'm assuming a place like Mavis wouldn't do that. I guess finding an independent shop would work. If I were to go the aftermarket route, one that meets CA emissions standards would be the wisest choice? Which brands are best? Want to try to get an idea of the price difference between one of those and OEM.

 
Rep Power: 210

not likely.....

thats like bringing your own food to a restaurant and asking them to cook it for you

 
Rep Power: 518

Some do, some don't. Call and ask.
If it were up to me, if it were my own shop, you would be charged more on the labor side to make up for lost profit from the parts.
And my only guarantee is that the installed part won't fall out on the ground through any fault of mine.
Call and ask. Duh.
I have installed customer supplied parts at the dealer.
Probably, as far as the cat is concerned. CARB approval.

You might look into a used setup from a low mileage salvage yard unit too. At least it would be all factory at a lower price.

Whichever one actually works?
Bad question for me. I deal with 99.9% OEM stuff.
Is Google not turned on in your area yet?
Search "CARB approved catalytic converter"

 
Rep Power: 0

"If it has an aftermarket header as well you may have to replace that too. The good news is the header is only $135: http://www.hondapartscheap.com/parts...fold-sohc-vtec"

I've noticed that some of the OEM headers on the Civics have a built-in Cat. How can I tell if I'd need this type? I have an EX.

 
Rep Power: 518

Parts catalog would tell what the car is supposed to have.

http://www.hondaautomotiveparts.com/

Your EX cat should have been under the car, not built in to the manifold.

Like #4 in this pic



I see someone beat me to it LOL

 
Rep Power: 186

All these threads/posts about people buying these cars used makes me feel so much better that I bought mine brand new and unmolested. What a pain for all these people who buy these cars used and seriously molested and have no idea of the general/major problems(head gasket) associated with these vehicles.