Please help my check engine light is on!

[Lani]

I was on my way to work this morning and my check engine light came on. I didn't notice anything wrong with the car such as hesitation or anything like that. On my way home I stopped at Auto Zone and had the code checked. The guy said something about the catalytic converter and something else...I can't remember. He said I probably didn't give my car enough time to warm up this morning which is why the light went on. The light is off now but should I still have it checked? He said it's not a big deal and not to worry about it but I am because I have a 20 min drive on the highway tomorrow and I don't want to get stuck somewhere. (nailbyt)

Any and all advice is greatly appreciated!

[P-Funk!]

As a guide - a flashing CEL means pull over (and probably a tow to a shop).

A solid (not flashing) CEL will let you know some emmisions equipment went out of range. If after 3 or so starts without the fault detected - it will go out. The code can still be retrieved later .

If the code comes back it is probably a worn O2 sensor.

[concept]

You don't have to "warm up" your car, so I doubt Mazda designed a circuit to trigger a warning light for that reason. As was mentioned, a check engine light typically tells you that a check of a component or signal boundary that reveals an "out-of-spec" condition will result in the light illumination. It is seldom a reason to not drive the car, although you shouldn't take too long to have the problem fixed.

Also, when you have someone read the code(s), always write down what they are and what they mean. There may be someone in here who has had the same problem and knows how to fix it without having to take the car to a mechanic.

[Lani]

As a guide - a flashing CEL means pull over (and probably a tow to a shop).

A solid (not flashing) CEL will let you know some emmisions equipment went out of range. If after 3 or so starts without the fault detected - it will go out. The code can still be retrieved later .

If the code comes back it is probably a worn O2 sensor.


Yeah. I was debating whether or not to have it towed while I was at work. Luckily my drive home is short and the auto parts store was on the way so I decided to give it a go. After all, it was performing just fine.... no loss of power, smoking or anything like that...

Update: I took the car in this morning and the Mazda dealer can't find anything wrong with it. They just said to keep an eye on it and if the light comes back on to bring it in. Hopefully it stays off but we'll see...

Thanks for the responses.

[fishdonotbounce]

Make sure to get those codes if it comes up again. That way we'll know exactly what the code is and help you figure out exactly what the problem is. I'm going to guess lean in bank 1 which, like P-Funk said, is usually the primary o2 sensor.

[bazooka joe]

ya mel, get the acutal code for us...unfortunatley not all the autozone guys know what they're talking about...could be a one time deal...

[Lani]

How can I tell if it is the o2 sensor? What are the symptoms? I'm not noticing any foul odors and I'm still getting good gas mileage. But if it is (the o2 sensor), the check engine light will come back on eventually right?

[slavrenz]

I was on my way to work this morning and my check engine light came on. I didn't notice anything wrong with the car such as hesitation or anything like that. On my way home I stopped at Auto Zone and had the code checked. The guy said something about the catalytic converter and something else...I can't remember. He said I probably didn't give my car enough time to warm up this morning which is why the light went on. The light is off now but should I still have it checked? He said it's not a big deal and not to worry about it but I am because I have a 20 min drive on the highway tomorrow and I don't want to get stuck somewhere. (nailbyt)

Any and all advice is greatly appreciated!

Come on guys, no one could figure this one out? :) I will bet $1,000 that the code is P0421 - warmup catalyst efficiency below threshold. Basically, it means your front catalytic converter (near the exhaust manifold) is shot. This is almost never an O2 sensor issue with our cars, although it is technically possible.

You've got 4 options:

1. Ignore it - it doesn't mean that your cat is physically falling apart, just that it is no longer able to chemically reduce your emissions. Bad news if your state has emissions inspections.

2. Replace with aftermarket cat - go to RockAuto.com, and order Walker Part No. 16220 for $260. Please, for god's sake, don't mess with a universal cat or one of those cheapies on eBay. Ask me how I know (chair)

3. Replace with OEM cat - this is gonna run between $600 and $1000, depending if you order the cat yourself or have it installed. Most expensive, but guaranteed to last.

4. Install CEL nonfouler - search the forum for this, but is basically just tricks your O2 sensor into thinking your cat is working fine. Won't fix your cat, but it will get rid of the Check Engine Light (CEL).

[fishdonotbounce]

lol slav for some reason that never occured to me despite it being posted a million times before. Kudos. Another thing you can do is post a WTB thread for a stock header (or whatever you wanna call it). A lot of people buy an aftermarket header and want to get rid of their stock one but can't because usually no one wants it.

[Lani]

Alright the check engine light came back on. I had the code read again and it's P0421- Warm up catalyst below bank 1. I spoke with a mechanic and they would like to start by replacing the o2 sensor since I am not noticing any performance problems.. Problem is which sensor do I replace? There are two and I have to order one before I bring it in on Tuesday. This sucks...:(

Wait should I be even driving it in? Or should I have it towed? The car runs fine... I just don't want to make the problem worst.

[fishdonotbounce]

It is your catalytic converter. I wouldn't even take it in unless you have some warranty that is paying for everything. You're going to end up paying 100 for the o2 sensor and 100 for them to replace it when it takes two seconds to unscrew it and put the new one in. Your check engine light will come back and then they'll tell you it's the cat. Put up a WTB thread for either the whole manifold assembly or just the cat. I sold mine for 50 bucks a few years ago.

[MaxPower]

Definitely, buying the new Walker converter from RockAuto OR buying a used front converter from this forum are very cost-effective (legal) solutions.

Keep in mind the car has two catalytic converters. The one you need is the one just after the exhaust manifold on the front side of the engine. There's another one below the car--you do NOT need to change this one.

[Lani]

2. Replace with aftermarket cat - go to RockAuto.com, and order Walker Part No. 16220 for $260. Please, for god's sake, don't mess with a universal cat or one of those cheapies on eBay. Ask me how I know (chair)


So going to Midas for a new cat would probably be a bad idea then? (shrug)

[fishdonotbounce]

Yes. Bad idea. They will have you pay approximately 600-1000 dollars like we said before. Your car will be FINE until you get the new catalytic converter. Put up a WTB thread in the Protege For-Sale section and I'm sure you'll have a cat in no time. Once again, you need the first cat or primary cat which is the one that you see on the front of the engine like max said.

[MaxPower]

Definitely don't go to Midas! The car won't have any driveability problems because of the problem with the catalytic converter--it'll just be emitting more pollution than usual.

[concept]

Any muffler shop can install a CAT, but I would make sure that the shop also has a smog-check machine, if possible. That way, they can verify that the new cat solves the problem and that you'll have no surprises when it comes time for your next smog check.

[mckernan]

come on guys, no one could figure this one out? :) i will bet $1,000 that the code is p0421 - warmup catalyst efficiency below threshold.

winnar!

[Lani]

I started up my car today (it goes into the shop tomorrow morning) and whoa the fumes! (braindead

[MaxPower]

What did you decide to do?

[Lani]

What did you decide to do?


I dropped it off this morning at a local shop. I spoke with the mechanic and told him it was probably the catalytic converter and he hesitated a bit, he said "Well it could be something else. Let's hope it's not the catalytic converter. I'll check the car out and let you know". I'm waiting for him to call me back... :(

[fishdonotbounce]

I'll say it again. While the car is in the shop, post up a want to buy thread saying that you're looking for the front cat or just the whole mani/cat setup. Shouldn't run you more than 60 bucks shipped. Much better than the 1000 dollars that you'll end up paying by having your mechanic order it. It wouldn't be his fault either because that's how much he'll have to get it for. And that way you'll also know that you have an OEM part, even though it will be used. There are plenty of people that would love to get rid of their old manifolds cause they're just collecting dust in their garage.

[ucMP3]

I have my old front pipes with the primary catalytic converter sitting in my basement right now. I could sell you the secondary catalytic converter too if you would like. :D Everything back to the axel is sitting in my basement. I'm not sure how much they would typically go for, but I'm not trying to make an extra buck or anything, so... Anyone know what they have sold for on these forums in the past? Shipping will probly be a fair amount due to how heavy it is.

*Well, I just heard a $60. I wonder how much shipping would be from Ohio to Conneticut?

Let me know if you are interested. I can get a couple pics up on my photobucket account for u if u want.

[fishdonotbounce]

Shipping will end up being around 30 if I'm not mistaken. That all depends on the size of the box.

[Lani]

The mechanic called me back and said I need two new catalytic converters and two new o2 sensors-- which seems like absolute b.s. to me! He wanted $754. just to replace both of the o2 sensors and do some 44k B & G treatment to clean out the catalytic converters-- of which need to be replaced but this will at least by me some time in his opinion. He did the 44k treatment and with the diagnosis it cost me $138. total rip off!

[fishdonotbounce]

Jesus man why didn't you listen to us? Now PM ucMP3 about his catalytic converter, buy it for under a hundrer bucks, spray down your exhaust manifold bolts with PB blaster a few times while you wait for it to come in the mail, and replace it. Doesn't take long at all and can be done with a socket set and a pipe to use as an extension or a breaker bar. Just make sure the engine is cold and be careful not to snap the bolts. We told you he'd try to rape you. Oh and 750 for 2 o2 sensors is absolute bullshit. It takes 5 seconds (literally) to unbolt the o2 sensor and put in the new one. Each costs about 100 bucks. If you do end up needing an o2 sensor, buy it yourself and install it yourself. Tell that mechanic to fuck off.

[Lani]

Jesus man why didn't you listen to us? Now PM ucMP3 about his catalytic converter, buy it for under a hundrer bucks, spray down your exhaust manifold bolts with PB blaster a few times while you wait for it to come in the mail, and replace it. Doesn't take long at all and can be done with a socket set and a pipe to use as an extension or a breaker bar. Just make sure the engine is cold and be careful not to snap the bolts. We told you he'd try to rape you. Oh and 750 for 2 o2 sensors is absolute bullshit. It takes 5 seconds (literally) to unbolt the o2 sensor and put in the new one. Each costs about 100 bucks. If you do end up needing an o2 sensor, buy it yourself and install it yourself. Tell that mechanic to fuck off.

I did listen. I posted in the WTB thread about a catalytic converter. I'm just waiting on people to post pictures then it's practically a done deal.

[Lani]

I have my old front pipes with the primary catalytic converter sitting in my basement right now. I could sell you the secondary catalytic converter too if you would like. :D Everything back to the axel is sitting in my basement. I'm not sure how much they would typically go for, but I'm not trying to make an extra buck or anything, so... Anyone know what they have sold for on these forums in the past? Shipping will probly be a fair amount due to how heavy it is.

*Well, I just heard a $60. I wonder how much shipping would be from Ohio to Conneticut?

Let me know if you are interested. I can get a couple pics up on my photobucket account for u if u want.


Pictures would be great! And how much mileage does your catalytic converter have on it about?

[justanothermp5]

wait so the guy did the 44k treatment without telling you and then charged you for it?

[Lani]

wait so the guy did the 44k treatment without telling you and then charged you for it?

I told him to do it thinking that it would help.

[ucMP3]

What is 44k treatment?? I've never heard of that before.

Also, if you get universal 02 sensors and wire the sensor into the harness yourself ( much easier to do that it sounds) those universal sensors are around 69.99 usually I think... They might be a bit more than that now tho, I haven't had to buy one in a while.

*O, and I have both cats if you need both... They have a little over 100k miles on them, It was between 100k & 105k when I installed the new exhaust IIRC. The second cat is in a longer pipe tho, the shipping box would be a bit bigger with that one, although probably not as heavy as the primary cat/j-pipe.

[Lani]

What is 44k treatment?? I've never heard of that before.



The 44k B & G treatment supposedly cleans out the catalytic converter along with the o2 sensors-- or at least that's what the mechanic told me.

[fishdonotbounce]

Your mechanic suckered you out of your money. He probably threw some fuel injector cleaner in the gas tank and called it a day. You got charged $134 for him plugging the CEL machine into the easily accessible under your steering column, and putting in a 4 dollar bottle of crap in your gas tank.

[Lani]

Your mechanic suckered you out of your money. He probably threw some fuel injector cleaner in the gas tank and called it a day. You got charged $134 for him plugging the CEL machine into the easily accessible under your steering column, and putting in a 4 dollar bottle of crap in your gas tank.

Sounds about right (although that 44k stuff does have a good reputation if you do a search on it).

[MaxPower]

Let me get this straight. You post on this forum asking for advice, plenty of people with experience respond and explain to you exactly what you need to do to get this done right at bottom dollar, and you IGNORE it and take it to some imbecile mechanic who rips you off?! Consider this a $140 lesson, money well spent if it keeps you from doing it again.

PLENTY of people are offering to sell you a cat. Give them $50-100, shipped for it, then take it to a DIFFERENT shop and have a mechanic install it (should cost $50-100). For the $134 you squandered, you could have had the problem fixed by now.

Argh, this is why people don't bother posting to help others.


Jesus man why didn't you listen to us? Now PM ucMP3 about his catalytic converter, buy it for under a hundrer bucks, spray down your exhaust manifold bolts with PB blaster a few times while you wait for it to come in the mail, and replace it. Doesn't take long at all and can be done with a socket set and a pipe to use as an extension or a breaker bar. Just make sure the engine is cold and be careful not to snap the bolts. We told you he'd try to rape you. Oh and 750 for 2 o2 sensors is absolute bullshit. It takes 5 seconds (literally) to unbolt the o2 sensor and put in the new one. Each costs about 100 bucks. If you do end up needing an o2 sensor, buy it yourself and install it yourself. Tell that mechanic to fuck off.

[ucMP3]

Its ok maxpower. Everyone has to learn. If you don't know much about your car, then you could get really worked up about a minor problem and make a rash decision.

Lani, I'll get some pics posted tonight of the j-pipe. Are you wanting to get the 2nd cat as well? Or just the primary?

[Lani]

Let me get this straight. You post on this forum asking for advice, plenty of people with experience respond and explain to you exactly what you need to do to get this done right at bottom dollar, and you IGNORE it and take it to some imbecile mechanic who rips you off?! Consider this a $140 lesson, money well spent if it keeps you from doing it again.

PLENTY of people are offering to sell you a cat. Give them $50-100, shipped for it, then take it to a DIFFERENT shop and have a mechanic install it (should cost $50-100). For the $134 you squandered, you could have had the problem fixed by now.

Argh, this is why people don't bother posting to help others.


Excuse me? I did follow the advice of people on the forum. I posted over the weekend in the wanted to buy section about the catalytic converter. I've received a few responses but no one has posted pictures as of yet. I am not going to buy something without knowing it's good or not because it's cheap. Also, every person that I've talked to has suggested replacing the o2 sensor. Mine ARE bad. I was there when the mechanic did the test right in front of me. I just wasn't willing to pay over $700. to have them replaced.

[concept]

Dang, this neighborhood has a tough crowd......

[ucMP3]

Dang, this neighborhood has a tough crowd......

Don't let a few angry people push you away. There are more than enough helpful people to offset.

[TORBFDL]

Lani, i had the same problem a few weeks ago. the CE light came on and when i had it checked it came up P0421- Warm up catalyst below bank 1. I was in a panic. I only had the car(01' ES 2.0) for two weeks. after looking every where for help I bought a new O2 sensor. it is the one after the first CAT. I have not had a CE light come on for 500 miles.

[ucMP3]

Lani, i had the same problem a few weeks ago. the CE light came on and when i had it checked it came up P0421- Warm up catalyst below bank 1. I was in a panic. I only had the car(01' ES 2.0) for two weeks. after looking every where for help I bought a new O2 sensor. it is the one after the first CAT. I have not had a CE light come on for 500 miles.

This will get rid of your CEL, however its not fixing the problem, only masking it temporarily. The reason that O2 sensor was out was becasue your catalytic converter is most likely not functioning properly and it will eventually tear through your new O2 sensor as well.

[MaxPower]

Great deal on an almost-new front cat... http://www.mazdas247.com/forum/showthread.php?t=123755629

[Lani]

Great deal on an almost-new front cat... http://www.mazdas247.com/forum/showthread.php?t=123755629


Thanks but I'm all set. I bought a catalytic converter last week from RockAuto.Com and had it installed yesterday. My car runs great and best of all, isn't polluting the environment. :)

[MaxPower]

Excellent. Should last you for a while.