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Discussion Starter · #1 ·
First post. My check engine light came on with the code P0421, warm up catlytic converter efficiency on Bank 1. Kia wanted $1300 to replace (off warranty), so I found a salvaged converter. Finding this salvage converter wasn't easy, since no one seems to know what Bank 1 is. There appear to be 3 cat converters on the Sedona, one off the front and back of the manifold, and the last just before the tail pipe. Kia told me that Bank 1 is the rear cat, closest to the firewall. So, I replaced with a similar salvaged cat converter.

However, my check engine light came back on the next day with the same code. Could we have replaced the wrong cat converter? I would guess that the odds are pretty low that the salvaged cat converter would have had the same problem as mine.

Frustrated!!

Ideas??
 

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Discussion Starter · #3 ·
Hi Murph

Thanks for your response! I find it interesting that you say the cats rarely fail. I've heard from salvage parts dealers that there has been a "run" on Kia Sedona cats as of late. Kia believes it has something to do with the low octane (87) gas used here in Canada. However, this is the minimum recommended octane Kia suggests, so I would think things would be OK.

As for the efficiency code related to an air leak, would this be associated with the cat converters? Also, if I were to look for an air leak, would it be easy to spot or are they rather inconspicuous?

Again, thanks for your response, it certainly does provide another lead in my cat converter saga.
 

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Air leak causes an effiecentcy code as theres to much air being drawn in for the combustion cycle, difficult to detect with modern control systems as they adjust themselves so much to maks these problems.
Check all vaccuum hoses for security and splits, any gaskets on the intake, sometimes spraying a bit of wd40 around intake joints and hoses will cause a stumble or rev this can be handy to find.
 

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I know this is a dead post but I'm sure there will be others with this problem. I have found, through much searching and doing, that if you do not have an intake/vacuum leak, have good fuel pressure and your o2 sensors are good (YOU HAVE TO CHECK ALL THESE) and you do not hear a rattling noise or smell odd smells from the exhaust or a glowing cat (DEAD GIVE AWAY OF A BROKEN OR BAD CAT) then more than likely the P0421 code is due to a programming glitch in the ECM. Many cars have this problem, and many more will due to the governments always trying to mandate companies to control every aspect of everything. I mean, a PRE-CAT, REALLY???? Come on....

Anyway, enough venting. Get 2 long, and I mean long ones to make sure you don't damage the sensor on the o2, things called "spark plug anti-foulers". O2 sensors use the 18mm threaded ones. They are meant to go on spark plugs when the valves or rings are going to get a little more life out of the engine. What you do is remove the DOWNDRAFT (the one after the "pre-cat") sensor which only reads the exhaust from the cat to tell the ECM if it is bad, and install it as a spacer. It removes it from the direct draft of the exhaust, and fools the ECM into believing everything is fine. But, this is only a fix if all other possible problems have been investigated (LEAKS AND FUEL). It will extend the life of your cat.
 

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I know this is a dead post but I'm sure there will be others with this problem. I have found, through much searching and doing, that if you do not have an intake/vacuum leak, have good fuel pressure and your o2 sensors are good (YOU HAVE TO CHECK ALL THESE) and you do not hear a rattling noise or smell odd smells from the exhaust or a glowing cat (DEAD GIVE AWAY OF A BROKEN OR BAD CAT) then more than likely the P0421 code is due to a programming glitch in the ECM. Many cars have this problem, and many more will due to the governments always trying to mandate companies to control every aspect of everything. I mean, a PRE-CAT, REALLY???? Come on....

Anyway, enough venting. Get 2 long, and I mean long ones to make sure you don't damage the sensor on the o2, things called "spark plug anti-foulers". O2 sensors use the 18mm threaded ones. They are meant to go on spark plugs when the valves or rings are going to get a little more life out of the engine. What you do is remove the DOWNDRAFT (the one after the "pre-cat") sensor which only reads the exhaust from the cat to tell the ECM if it is bad, and install it as a spacer. It removes it from the direct draft of the exhaust, and fools the ECM into believing everything is fine. But, this is only a fix if all other possible problems have been investigated (LEAKS AND FUEL). It will extend the life of your cat.
how do you check your fuel pressure? I don't have the special fitting Kia recommends, and I can't figure out how to disconnect the fuel lines.:eek:
 

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Sorry, I just barely logged back on first time in months. You have to get a barbed t that fits the inside of the hose, believe its 3/8 or 1/4, and cut the lines and put it on with clamps. Then you'll have to get a cap. That's the only way that I've found to check it.
 

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Is there a search engine in this forum? Where you can type in a subject and get the quotes you need.

Ny 2002 Sedona with 200K lost power a few month ago. After changing over the last few month the fuel pump, the fuel pressure regulator, spark plugs, injectors, timing belt with CPS and IFS I am now looking at the bank 1 cat. From what I can see some of the five bolts on the manifold connection have the nuts on top. Or are the once from the top bolts? How do you get to those? I think of bending a 12 mm (possibly I need a 7/16 and a hammer to force it on the corroded nuts) box spanner 90 degree very near to the top so that I can catch the nut from the top position. Perhaps I drill them out. Does anyone have a better idea?

I am not complaining. The car served me very well all these years and looks inside like new but I just put new rubber, brakes, ball joints and AC compressor on the car before the loss of power.

Thanks for helping.
 
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