Question about 2002 Mazda 626

12 Answers

CEL flashes(Code P0421), High pitch squealing @ start up, & Horn blows for no reason

The car has around 108,000 miles. The CEL flashes on & off. It comes on in the morning and by the evening it goes off. The CEL may stay on one day and the next day it may not come on at all. The car also makes a high pitched squealing sound when starting the engine. And when the car is off, parked, and doors are locked the horn will just begin to blow for no reason. This happens at random times without any warning.

Within the past month I have had a new PCV valve installed, transmission fluid flush, fuel system tune up, complete diagnostic check/scan, new spark plugs, ignition wire set, valve cover casket, and an air induction cleaning service. These services were done by Firestone & Precision Tune.

Please help. I don't know what else to do. I can't afford to keep getting diagnostic scans and not get the problem fixed. I have been to the Mazda dealership in my area but their customer service was terrible & the rep didn't seem to listen to me or let me explain the problems. He just gave me the "you will have to get a complete diagnostic scan/service" line. "And that will cost you around $165.

My car is paid for & I really do not want to purchase another vehicle. What can I do? Can my problems be fixed?

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  • 2 more comments 
  • Sequeya
    Sequeya Oct 03, 2008

    I'm a little confused based on 2 or 3 different answers that I have received. Is the problem an electrical problem, a transmission problem, or both??? I don't want to pay for a diagnostic check if I shoud be getting the transmission checked or vice versa?????

  • Sequeya
    Sequeya Oct 03, 2008

    CEL = Check Engine Light

    Front CV Drive Axle was replaced on 9/9/08

    Alternator belt was replaced on 8/21/08

    Car does not have an alarm

  • Sequeya
    Sequeya Oct 05, 2008

    Thank you very much! I really appreciate such a detailed answer. It really helped a lot. I have a much better understanding of the problems/issues. Your solution has been very helpful. Thanks again!

  • Sequeya
    Sequeya Oct 07, 2008

    Good morning Ladies & Gentlemen,



    I went back to the Mazda dealership on Saturday, Oct 4. I had to make an appointment to have the "complete" diagnostic scann/test. I took the car in this morning at 8:00 AM, Oct 7. They quoted me a price of $484.00 to run a "complete" scan. They said the testing would take all day. I was also told that if "wiring mapping/testing" (please excuse my terminology) is required that it would be an additional fee/cost and that it would take more than one day to completely diagnose and possibly could take up to a week.



    Can someone please tell me if this sounds legit? If not, what should they be doing? Is there any questions or things that I should be asking? Once the problem is diagnosed I was thinking about taking the car to another shop to have some of the work done. If needed, I was only going to let Mazda do work pertaining to the wiring system since they are the experts on Mazdas. If it is other issues like the O2 sensor or catalytic converter, I was going to take it to another reputable shop in order to save money. I have a feeling this is going to hurt my bank account a little but since my car is paid for I think it is more economical than purchasing another vehicle and having car payments for another 3 to 5 years. Someone, Please provide any input that you can on this matter.



    Thanks in advance,

    Sequeya





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12 Answers

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Diagnostic check is necessary as you have replaced many parts still not got your problem solved so to confirm your problem and come to some conclusion the check up is very much necessary.and what problem you r getting can be caused due to multiple reasons but it can be fixed for sure that i can tell you.diagnostic check will lead you towards the proper directions.

Posted on Oct 05, 2008

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Sounds like your o2 sensor or catalytic converter. I would change out both. If you still need any help let me know. Please take a moment to accept and rate my solution accordingly. If you need further explanation I can provide that as well.
Thanks,
lee

Posted on Oct 04, 2008

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  • 2,039 Answers

When the check engine light flash it mean if you continue to drive you might damaged the catalytic converter that because the engineis not burning all the gas engine misfired is it worst when its raining let me now pierre

Posted on Oct 04, 2008

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Hi, Assuming that thats the only code you got.
the definition of the code is "Warm Up Catalyst Efficiency Below Threshold"
Since its turning on and off, I guess the CAT converter (catalyst converter) is malfuctioning. You may want to replace that with a local mechanic.
Since its expensive, I would first suggest you to check the oxygen sensor. Since it might also throw up this error code and fixing it would be cheaper than CAT converter.
If Oxygen sensor is good, you have to replace the CAT converter to fix it.
I know mazda dealers charge a lot. They charge ~80$ just to run diagnostics and tell you the code, which you can get it for free from some places like Autoparts zone etc...
and dealers normally dont bother about old cars. (thats why poor customer service ...) I had that experience when I once wanted to fix some product recall for my car (mazda 626 98) ...
:)


Posted on Oct 03, 2008

  • Karthik P Oct 03, 2008

    and also sign up in www.mazda626.net


    you get lots of information for people owning mazda 626 ...



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  • 188 Answers

I checked out this web site. There is also more information here.

http://forums.mazdaworld.org/index.php?showtopic=7044

Posted on Oct 03, 2008

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  • 208 Answers

Hi,

Some possibilities from the service manual:
Code P0421
* Crankshaft position sensor malfunction
* Spark plug malfunction
* Coil malfunction
* MAF sensor contamination
* Vacuum leak between MAF sensor and throttle body
* Fuel pump malfunction
* Fuel line restriction
* Fuel filter restriction
* Fuel system leakage
* Purge control solenoid valve malfunction
* PCV valve malfunction
* EGR valve malfunction
* Vacuum hose damage or incorrect hose routing
* Related connector or terminal malfunction
* Related wiring harness malfunction

Good luck...

Posted on Oct 03, 2008

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P0421 (warm-up catalyst system below threshold) code

Posted on Oct 03, 2008

  • 3 more comments 
  • Todd Gale
    Todd Gale Oct 03, 2008

    DEFINITION-CATALYST EFFICIENCY LOW-BANK 1. EXPLANATION-THE OXYGEN SENSORS MONITOR THE CATALYTIC CONVERTERS ABILITY TO STORE OXYGEN. PROBLEM CAUSES- 1. CATALYTIC CONVERTER DEFECTIVE (FAILURE POSSIBLY DUE TO #2,3, OR 4) 2. ENGINE MISFIRE OR RUNNING CONDITION. 3. LARGE VACCUM LEAK 4. ENGINE OIL LEAKAGE INTO EXHAUST-VALVE GUIDE SEALS, PISTON RINGS. THE PCM HAS DETERMINED THAT THE WARM UP CATALYST EFFICIENCY FOR BANK 1 IS BELOW TRESHOLD FOR THE CURRENT ENGINE OPERATING CONDITION. (BANK 1 IDENTIFIES THE LOCATION OF CYLINDER #1, WHILE BANK 2 IDENTIFIES THE CYLINDERS ON THE OPPOSITE BANK).

  • Todd Gale
    Todd Gale Oct 03, 2008

    "Today exhaust gas of gasoline engines is typically treated with “Three Way Catalysts” (TWC). The catalyst converts the pollutants CO, NOX and Hydrocarbons into harmless compounds like CO2, H2O and N2 by chemical reactions. Lambda-Sensors control the air fuel ratio of the engine and catalyst performance in order to get the best possible conversion of the pollutants.

    Modern lean burn engines have other options. Here the pollutants in the exhaust gases are only partially converted by a TWC function i.e. CO and Hydrocarbons. For the remaining NOX a so called NOX Storage Catalyst (NSC) is employed, which chemically stores NO and NO2 during lean burn phase. For the conversion of stored NOX the engine is periodically shifted to fuel rich operation."

    When the engine is shifted into rich mode the cat monitor is only measuring O/O2 retention in the cat. A properly operating cat will cause the monitor to have a slow response as the O is stripped out of the cat. A bad cat doesn't retain O/O2. A bad cat will cause the monitor sensor to have a reading that mirrors the primary O2 sensor(actual O2 sensor that determines fuel mixture). In this case a good cat monitor, that is fast responding, will fault a cat earlier than a lazy cat monitor. If anything a primary O2 is more likely to cause a P0421 as the engine will be running richer and the cat will have no excess O to give up. Problem is when an O2 gets bad enough to do that it will code either "lean" or "lack of/slow switching". So, if you have a P0421, and no codes for the primary sensor to go with it, it a darned near certain there is a problem with the cat.

  • Todd Gale
    Todd Gale Oct 04, 2008

    Unfortunitly, it can be both. The issue is the fact that the problem can be related to one or more of the five things I listed in my post. Without testing, one by one, you cannot know for sure. My suggestion is to take it to the mechanic and do not tell him you knoiw what is wrong and see how he responds. If he says it is the Cat. Converter, ouch, your screwed, but if he says it is just a bad o2 sensor, great, he'll reset the computer and all should be well. Or you can invest in your reader and test the compnents on your own. It is not that hard, but require some level of understanding of electrical and voltage and output. Again, my qadvise is take it ti the mechanic, seeing as if it is the CC, you are not replacing that without a welder anyhow. Please let me know if there is more I can do for you.

  • Todd Gale
    Todd Gale Oct 04, 2008

    The high pitched squealing sound is limited to starting, or gassing the engine. This is a loose or badly worn belt. Replace the belt, or check for tightness. Usually the alternator or the Smog pump is loose.



    The horn problem is suspect. That may be a bad horn relay, but I would first look for wiring going through the firewall, into the passenger compartment. Follow the line from the horn itself to the firewall, and the inside. It sounds like somewhere along the line you may have a short, and since wires are known to constrict and expand depending on weather, you may be experiencing a short somewhere in that wire. Check the wire, if you cannot find any bad areas, replace the horn relay, it should cost about $12.00.

  • Todd Gale
    Todd Gale Oct 07, 2008

    Well, today you got your most important lesson about cars. Dealerships don't do anything cheap and they usually require much more unnecessary diagnostics than most cars need in their lifetime. Your best and smartest bet is to find a reputable local shop that specializes in Mazda. This can be done through one of two methods. In most states there is a Bureau of Automotive Repair (BAR) or Department of Automotive Regulation. These are government agencies that oversee the automotive repair industry in each state. Although they will probably not recommend a hop to you, they will have public records of those shops that have had complaints filed against them and those are the shops to avoid. The second method is to go to the Better Business Bureu website and check for a shop in your area, for compliments, complaints and an overall rating. This will assure you are getting the what should be considered a fair and reasonably knowledgeable person to diagnose, quote and fix your car. The Diagnostics should cost no more than $100.00 total, entire car. Most good shops will apply some or all of that amount if you choose them to do the work, ask in advance. Ask fora copy of the results. You are entitled to this and are paying for it. It will be a computer readout from the reader showing the fault codes and a description of the problem.



    Lastly, it does not even sound like this is an issue that would require even considering a new car. It should not make that much of a big dent in your bank account, as compared to a new car and it sounds like this car has been pretty reliable over the years and you sound like the kind of person who does the maintenance regularly, so it should last for more than a few more years. Remember, certain parts are designed and bound to fail over time. All of the components related the O2 sensor and CAt. Converter are exposed to extreme heat and will fail at some point.



    You shold never throw away a good pair of shoes just because you broke a shoelace.OK, I only used one joke.

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Can i ask what is CEL?

the high pitch squealing sound is coming from a loose belt of the alternator. as you start the engine, the battery would be charged right away by the alternator and if the belt is loose, it will squeal.
the horn that would honk with out any reason could be the alarm being triggered by vibration.

i hope i was able to help,

tnx 4 using fixya,

drcool

Posted on Oct 03, 2008

  • francis rivero Oct 03, 2008

    hi seqhicks,

    have you seen my solution?

    just noticed that i don't have a rating and i am just wondering if you saw my solution.

    tnx 4 using fixya,

    drcool


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Dear sir/madam,

Flashing HOLD light indicates major Transaxle trouble.. check out


thanks
good luck

Posted on Oct 03, 2008

  • Asfiya Ahamed
    Asfiya Ahamed Oct 03, 2008

    Sir,

    Some possibilities from the service manual:

    * Crankshaft position sensor malfunction
    * Spark plug malfunction
    * Coil malfunction
    * MAF sensor contamination
    * Vacuum leak between MAF sensor and throttle body
    * Fuel pump malfunction
    * Fuel line restriction
    * Fuel filter restriction
    * Fuel system leakage
    * Purge control solenoid valve malfunction
    * PCV valve malfunction
    * EGR valve malfunction
    * Vacuum hose damage or incorrect hose routing
    * Related connector or terminal malfunction
    * Related wiring harness malfunction

    P0421= Warm Up Catalyst Efficiency Below Threshold Bank 1

    As for the water the cats/connetor clamps tend to leak water on our
    exhaust systems when they get older for some reason, but it should be
    better after the cat replacement.
    If its coolant, take the rear
    engine over off and stick a flash light down there behind the motor and
    see if you can see red crusty looking stuff coming off the rear coolant
    crossover pipe.

    thanks
    good luck





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Sounds like this can be an annoyance, seems to me you have a bad electrical connection in the steering column around the ignition switch, or the switch it self can be bad.
but it is "kinda" hard to tell with out looking at it. but i would start there.

Posted on Oct 03, 2008

  • kristopher betzler
    kristopher betzler Oct 03, 2008

    oh and the code can be a bad (O2 sensor) or (catalytic converter) needs to be replaced, i would start with the O2 first

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Check all ur wiring components , battery and battery oil.

Posted on Oct 03, 2008

  • mohammed marika thambi
    mohammed marika thambi Oct 03, 2008

    IF ECU still read with #2 cyl misfire. Then , hooked it up and check that #2
    injector was bad. Replaced 2nd injector..after that it wll work fine

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I would be confused as well by the answers, some are shooting in the dark on this issue, cat monitors are not O2 sensors, you may need a new cat but first check the the tailpipe levels of CO, cat monitors fail just like any other sensor, don't blindly replace a catalytic converter until the sensor has been monitored for a fault, the fact it flashes on and off indicates to this long time smog tech that the sensor is suspect before the cat is.

Posted on Oct 04, 2008

  • yadayada
    yadayada Oct 04, 2008

    thanks For Trying is not an fair rating, the info I provided is clear and correct, what answer are you looking for??

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