Hi,
I just bought 2002 mazda millenia S with 103k on. Last week check engine light came on. I took it to the mechanic and he said that both the right and lthe left front catalytic converters have gone bad. Computer code 421, 431. He gave me an estimate of around $2000 ( $707 for each converter and labor). He told me that mazda covers these converters only upto 80K miles[:@]. I have found some interent sites where same part is priced around $420-$450 each.Unfortunately i don't have any other mechanic in town who can read the codes of mazda. Dunno if this guy is tryin to rip me off? Any advise will be highly appreciated..thanks

 

Is not too unusual for Catalyst failure. Just put one on a 2001 Milly S with only 62k on the ODO. I do find it extremely odd however that both converters would fail at the same time. Little RED flag there. I think I would find a way to get the codes double checked just as a safety. Many major auto parts stores (ie Autozone) will do an OBDII code check for no charge in hopes they can sell you a part. Might make a few phone calls and see if any local ones do. Wouldn't hurt anyway.
Those codes are correct for catalyst efficiency by the way.

 

babyhuey
Thank you so much for such a detailed and prompt reply . I will give call to autozone and other auto stores around. Fingers crossed!

 

Same here somali. Hope they only pull up a evap leak code or something. Just sounded a little on the weird side that both cats went bye bye at the same time. Give a post back if they come up with any codes or anything OK. Here to help and give a little backup.

 

on the earlier cars(we have 2 99 s') the 0421/31 usually means the post o2 sensor is dying/dead. i get that code occasionally, and just erase it, but it comes back after a few months. usually o2 sensors start to slow down as they are dying, and the ecu will throw the code. i believe there was a tsb about the codes, and the post/rear sensor. dunno if it applied to your my, tho.

 

kennin is right. There is a TSB for the rear or downstream O2 sensors actually being overly sensitive and throwing a Cat efficiency code. I do not put much validity in doing that on higher mileage cars. If that would have been an issue it would have occured well before 100k miles. Kind of get forced into replace sometimes if car is out of regular warranty that would pay for O2 but still within emissions that buys the CAT. Unless the updated O2 has been installed already with records,Mazda will not honor the CAT replace. Basically customer has to pay for an O2 and then when light comes back on the Cat gets replaced under emissions. Below is excerpt from TSB in question.

TSB: 01-003/01
MIL ON - DTCS P0420 P0421, P0430 P0431
APPLICABLE MODEL(S)/VINS
All 1997-2000 Millenia S.

DESCRIPTION
Some vehicles may exhibit MIL illumination with DTC(s) P0420/0421 or P0430/0431 stored in memory with no driveability concerns present. This condition may be caused by an overly sensitive rear oxygen sensor(s), which falsely indicates an emissions concern and a DTC to be stored.

 

Hi,
Thats means I need to change the O2 sensor? or stick with the same plan of havin autozone/ or some other local auto store to recheck the check engine light (as babyhuey recommended). I tried to understand kennin's and ( babuhuey's reply to that post ) but some of the terms were too technical for me. I apologize if i am sounding stupid.

 

for BOTH cats to die at the same time is really rare. you should first try to reset the ecu. places that will READ the codes dont like to reset, iirc, they are not supposed to. oxygen sensors dont just die, the start to slow down as they get older. kinda like me. think of the sensor as a pendelum, going back and forth really fast. it does other things, too, but i am using this as an analogy. over time, it becomes contaminated, and cannot go as fast all the time. the ecu is looking for a certain speed, and if it slows down, or "hiccups", the ecu might throw the code, and the ce lites up. ce means "check engine", as in see if a certain part/system is bad, or is malfunctioning. it dont mean change part, just check part/system. so, what a lot of shops do is note which codes are thrown, clear them, test drive, and see if they come back. if not, release the car, but record what the code(s) were for future reference. if the lite comes back on, and the same code(s) are there, it is more evidence of a part/system being, or about to, go bad. ce lite on merely means car is sick, it needs to see the doctor, but it can be driven there. if the ce lite is FLASHING, that means the car is REALLY sick, and needs to go NOW; if you keep driving it, it will get worse.
i have my own scan tool that also can reset. you can get one for about a hundred bucks, for about 2 hundred, you can get one that will read out real time data, which is great for o2 sensors. i have had the 0421/31 codes several times, and i reset, test drive, ce lite stays off. i KNOW something in this system is going, but not this minute. in preparation, i already have 4 o2 sensors, they are fairlty cheap. when the time comes that the lite wont reset, i will change them first. if that dont do it, THEN i will change the pre-cat(s).
i am NOT saying the cats are not bad, they very well could be. but, if the only codes are 0421/31, and you can get them reset, if they dont come right back, you are safe FOR A WHILE. i would take this as a warning, you will eventually have to change out something. if you plan on keeping the car for a while, and have some mechanical ability, you should invest in a scan tool.

 

keninn,
Thank you very much for taking a time to expain terms at detailed level.I dont mind buying a scan tool as i have already paid mechanic $190 for two scan runs ( $96 for each run ). But the problem is that i am not good at all with mechanical stuff. As far as reseting of check engine light concerns, some1 told me that if you take the positive terminal of the batter off , it would reset the check engine light. I did that and check engine light went off . But it came back again after 100 miles. I unhooked the battery again and it came back after 30 miles. After that i took to the mechanic and he told me that the fornt catalytic converters are bad. I really wanna keep this car . I had montero before.NO problem. I had mazda 626 . NO problem. In this car everythin looks solid. Engine is neat and clean and overall its a great looking car. Could you please tell me that unhookin battery resets the computer or not or it it is something that a scan tool can only do or do I need something else . I again appreciate your time and help .
Kind regards

 

No apology needed somali and you are definitely not sounding stupid!!! Everyone has a different degree of technical knowledge on car stuff. Am very glad of that because if everyone knew all about it, I would be out of a job.
Agreed again on what kennin has said. A code being set does not point to instant parts replace but instead is there to give the technician a starting place on what to look for. I recommended getting the codes double checked at Autozone because the two together sounded a bit suspicious and getting a 'second opinion' or confirmation never hurts anytime. I would hold off on the O2 replace as well untill more information is gained. Would also not hurt afterwards to clear the codes and seeing what gets reset later down the road. Keep in mind that the fault indicated by these codes will not leave you stranded, car will never not start or run rough. Only means that the emission level out of your tailpipe is possibly higher than normal. Only downside is that with CEL on or catalyst efficiency test not passed, you will not pass any state inspections if they even apply in your area. Otherwise is not a big deal.