I have problem with myMazda Protege 1998 LX (Mileage: 150K now). The "Check Engine light" came ON (OBDII P0421: Warm Up Catalyst Efficiency Below Threshold...)a while ago. Mazda dealer checked it and cleaned the entire fuel system at that time. It came backa few months later, they said nothing wrong and turnedthe CEL off. Since then I have manualy turned CEL off by disconnecting the batterry sometimes. ButI recognized that the cycle is getting shorter and shorter.

Based on below MSN Auto site, ECL problem with this car seems common. Does anyone know if this is safe condition to drive? Ifthis ishurting my car, is there anyway to fix it?
http://autos.msn.com/research/vip/Re...&trimid=-1

I apprecaite any comment or suggestion.
Thanks

 

It needs a cat converter. There is an o2 sensor in front of the converter and behind the converter. The first o2 sensor is an input to the PCM for fuel mix adjustments above idle basicly. The second O2 monitors the efficiency of the catylitic converter. That is its only function. The PCM compares the o2 sensor readings and if they read the same or within a certain perameter of close it means the converter is not cleaning up unburned fuel like it is supposed to so it kicks that code.

 

Thank you hixx! Your message helped me clearup many other concerns. I have couple more questions if you don't mind.

1) If the converter is not cleaning up unburned fuel, would it be safe to drive, or possibly hurting my car or anyconcerns?

2)Would there be anycauses, which maydamaged the catylitic converter? Or is it simply typicallife cycle based onthe design?

Thank you again for your help

 

I wouldn't go for too long, only because you don't want to foul the O2 sensor too much.
http://www.ecatalyticconverter.com/m...98-22-cat.html

I got a Bosal Cat from these guys. They were pretty good to deal with. If you have a Foreign Autopart in your area, they can be pretty competitive to the prices above.

 

Converter damage can be caused by overheating the converter , basicly running too rich for various reasons like dirty injectors,plugs etc. Poor plating of the converter can also be the cause. OEM converters are platinum plated so of they get it wrong it breaks loose. I have had to replace converters on certain models at very low mileage. It will not hurt anything if it just lost the plating but if it is partially restricted it can cause engine damage in the long term. A visual inspection of the inside of the converter and a good tune would be a good idea.

 

Thanks for your comments, MazdaES and hixx.

I actually replaced the Exhaust Manifold about a year ago because of a crack that caused pretty bad exhaust fumes to the cabin. This was after I had started to see the CEL problem. I now feel that it was not coincident. May I assume that Cat was already partially restricted at that time and caused Exhaust Manifold to crack even before the engine damage?

1) Would dealer perform a visual inspection of the inside of the converter at reasonable cost or it’s easy to do it myself?

2) What’s the difference between Cat and Pre-Cat? Do I need to inspect both?

3) Recently A/C operations make the acceleration dramatically poor. Would it be possibly related to Cat problem?

 

In answer to your questions,

1. A Mazda dealer can perform an inspection for no more the $100. This should be a comprehensive inspection of all parts of the exhaust system. Where there's one blockage, there may be more.
2. In reference to the loss of power, Yes....

Keep in mind that dealer prices for exhaust parts is extremely inflated. You might get a better price at a local exhaust shop or one of the chains, along with warranty. You can probably get an inspection done for free or little cost at one of the chains also. Don't be afraid to check their work also. Demand that they bring you under the car and show you what was replaced before paying them. Lots of these places can be real scam artists...

You want them to replace your exhaust parts with Direct Fit parts as oppossed to universal parts. These will cost a bit more, but can be replaced in pieces (I.E. Just the CAT or Just the resonator) as subsequent repairs are needed. Look at your exhaust system now. Thats what it should look like after the work is done.

 

Hi All,

I apologize for not getting back for awhile. I just had a chance togo backto the Mazda dealer fora diagnosis ($85+tax) andreceived the followingfindings:

1) CEL: P0421 needs new converter (Z502-20-500) but O2 sensor seems fine at this time.
2) Timing belt is loose and needs replacement. I thought theywere kidding becasue they were the one who replaced it at 136K miles (2nd time)and my car is still at 150K currently. Since it's been driven for over 12K since last replacement so it'sout of warranty; they demandedme to pay another full price! Theytoldme '98 Protege is aged and that's why... Are theyfooling me?

Total chargecomes to about $1,500 (Cat+Timing Belt). After this inspection,my car isnow much harder to accelerate and noiser.Any advice would be greatly appreciated.

Thanks.

 

The timing belt job is a $250 USD item, add another $125 USD if you do the water pump also. Which, if you haven't done it ever, do it with the timing belt, since they have to take everything apart to get to it, put don't let them charge you double labor.

As far as the exhaust, shop the job around to a few different shops. Look at the link I gave you above, that is the actual cost of the cat. Even if they have to use some other parts and it takes the 5 hours, that job should be no more than $700, tops. I think there is about $500 worth of graft in that price.

What puzzles me is why would they look at the timing belt on an exhaust inspection, and how did they know it was loose?? Did they take the front of the engine off to look at it?? Not for $85... Hmmmmmm