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post #1 of 18 (permalink) Old 12-14-2010, 06:43 PM Thread Starter
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Need Advice RE: DTC's P0420 & P0430

The "Service Engine Soon" light came on the other day on my 1997 Thunderbird LX Sport, so I stopped at AutoZone and had the DTC's pulled - they came out as P0420 (catalyst efficiency low - bank 1) & P0430 (catalyst efficiency low - bank 2). The guy at the store told me that meant the converters were bad. My car, which (naturally) has a 4.6 liter V-8, has 162,000 miles on the odometer and I'm reasonably sure the converters are original equipmment. I have some questions regarding this issue and need some answers/advice:

1. Is it possible that just some of the O2 sensors are bad and it's not really the converters, or is it more likely that it's the coverters themselves that are bad?

2. Is it normal for converters to go bad with 162,000 miles on them, or do they usually last longer? My car uses what I think is a higher than normal amount of engine oil, meaning I need to add a quart every 500-800 miles (I've been told it's probably due to worn/bad piston rings) and I'm concerned that excessive oil getting into the converters might have ruined them. I see, however, very little smoke of any kind coming from my exhaust, usually only when the car is at a standstill & idling. So, what do you guys think - did excessive oil consumption cause this or just age/mileage?

I need some opinions on this problem because I can't see replacing the converters with new ones if they'll just get ruined from excessive oil getting into them, too, and I can't really see spending the money for an egine rebuild as they car just isn't worth that type of expense. I also do NOT want to eliminate the converters as I care about the environment and Ohio has emmissions testing and the car would not pass without functioning converters.

Thanks in advance for any info anyone provides regarding this issue!

Dennis
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post #2 of 18 (permalink) Old 12-14-2010, 06:47 PM
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It could be the O2s, if they haven't ever been changed that'd be the first thing I would check out. I had an occasional P0430 a couple years back up until I replaced the O2s.

On a slightly unrelated note, I have and no longer need the entire stock exhaust off my car that I no longer need, didn't have any issues or leaks, save for a slight rattle coming off the 3rd cat (stray piece of metal between the cat and heat shield).

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post #3 of 18 (permalink) Old 12-15-2010, 09:26 AM
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I changed out my cats around 140K on my 97. I'm still running the original O2 sensors. P420 and P430 are cat specific codes. There are other specific codes for the front O2 sensors and the rear ones too. Certainly changing the sensors at 162K won't hurt anything except cost you some money. But I'd be taking a hard look at the cats. Find an exhaust shop that can do a back pressure test. Make sure also that you don't have any vacuum leaks.

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post #4 of 18 (permalink) Old 12-15-2010, 10:52 AM
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Yes, if you have those codes, then you have bad cats. Bad O2 sensors can cause other issues, and if you are burning oil you may need O2s as well, but if you have P0420 and P0430, you need cats. The oil burning certainly isn't good for the cat, but it isn't somthing that is going to destroy it right away. Plus aftermarket cats are cheap, so if you have to pass emissions just get a couple aftermarket ones and have an exhaust shop make some downtubes to weld them in.

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post #5 of 18 (permalink) Old 12-17-2010, 12:54 AM Thread Starter
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O.K., so I got on my T-Bird hard several times on the way home from work today and it seemed to be running stronger than it EVER did! So, I'm thinking that the cats aren't really plugged up by oil leaking into them and being crystallized by the intense heat - wouldn't the car be running poorly if there was a significant restriction somewhere in the exhaust system? Maybe they are just plain worn-out and in need of replacement due to the high mileage (I'm not really thinking it's O2 sensors, but rather the cats themselves), so I'm contemplating just going ahead and replacing both the cats AND the O2 sensors (due to the high mileage on the sensors).

Even if oil is getting into the exhaust and has contributed to the cats going bad, I'm thinking it's at a rate slow enough that a new catalytic converter assembly will last, hopefully, for the year or two longer that I have this car.

Among those on these forums who've replaced their catalytic converters with direct-fit aftermarket units, which brands seems to work best in terms of fitting properly and not having any leaks at the flanges or O2 fittings?

Dennis
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post #6 of 18 (permalink) Old 12-17-2010, 01:40 AM Thread Starter
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Quote:
Originally Posted by theterminator93 View Post
It could be the O2s, if they haven't ever been changed that'd be the first thing I would check out. I had an occasional P0430 a couple years back up until I replaced the O2s.

On a slightly unrelated note, I have and no longer need the entire stock exhaust off my car that I no longer need, didn't have any issues or leaks, save for a slight rattle coming off the 3rd cat (stray piece of metal between the cat and heat shield).
Brandon,

I think you are offering to sell me the stock converter assembly off of your T-Bird; thanks, I appreciate the offer, but I'm kind of anal about only putting new parts on my car (including some new parts that I didn't really need to replace)!

Dennis
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post #7 of 18 (permalink) Old 12-17-2010, 10:51 AM
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I run the spun cats on my cars. They are cheap, easy to fit due to the compact size, and still do a good job of cleaning up the emissions. All the cars I have put these on pass NJ state inspection with no issues.

http://cgi.ebay.com/ebaymotors/Magna...ehicleQ5fParts

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post #8 of 18 (permalink) Old 12-17-2010, 07:35 PM
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I have the same cats as MadMikeyL and they have been working great for over 2 years and many many miles. My bird is daily driven. They are passing the test of time and miles.

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post #9 of 18 (permalink) Old 12-17-2010, 08:36 PM Thread Starter
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Quote:
Originally Posted by MadMikeyL View Post
I run the spun cats on my cars. They are cheap, easy to fit due to the compact size, and still do a good job of cleaning up the emissions. All the cars I have put these on pass NJ state inspection with no issues.

http://cgi.ebay.com/ebaymotors/Magna...ehicleQ5fParts
Quote:
Originally Posted by supergordo View Post
I have the same cats as MadMikeyL and they have been working great for over 2 years and many many miles. My bird is daily driven. They are passing the test of time and miles.
Thanks for the advice/opinions guys, but in addition to being anal about only putting new parts on my T-Bird, I'm also anal about only putting direct-fit or parts specifically designed/engineered for my T-Bird on it, instead of universal parts!

So, anyone have any recommendations for DIRECT-FIT converters for our T-Birds?
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post #10 of 18 (permalink) Old 12-17-2010, 10:46 PM
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Quote:
Originally Posted by dmw_4814 View Post
Thanks for the advice/opinions guys, but in addition to being anal about only putting new parts on my T-Bird, I'm also anal about only putting direct-fit or parts specifically designed/engineered for my T-Bird on it, instead of universal parts!

So, anyone have any recommendations for DIRECT-FIT converters for our T-Birds?
Walker 50516 (Federal) or 50519 (Calif)
Magnaflow 23343 (Federal) or 41111 (Calif)
Maremont 652094
Eastern 30373

All Direct-Fit complete 3 catalytic units that will bolt right in. Expect to pay $300-$450, but you can swap it in your driveway.

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post #11 of 18 (permalink) Old 12-24-2010, 06:08 PM Thread Starter
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O.K., so my "Service Engine Soon" light went out today - why would it do that if the converters truly weren't working properly anymore? Converters don't "stop" working and then just "start" working again - do they?!!

Dennis
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post #12 of 18 (permalink) Old 12-24-2010, 08:09 PM
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Yes what happens is they work better the hotter they get so if by chance u got a cooler thermostat or plugs that's all it can take if your cats aren't working as good as new they do were out I know my Honda has this problem evertime I go on a trip the light goes off cause it gets the conniver good and hot the old motor burned oil and took the converter out, basically there not stopping up just not filtering as good as new I've got some eliminator that plug in between the rear 02s and u want have to worry about this let me know

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post #13 of 18 (permalink) Old 12-26-2010, 09:17 AM
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If the data from the upstream and downstream o2 sensors coincide too many times it will throw those codes. You can replace the converters or for a little cheaper just get some MIL eliminators for the downstream O2s and run them until they cause driveability problems. One downside to this is that the pieces of catalyst can get stuck in your exhaust pipe or mufflers if and when the catalyst breaks.

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post #14 of 18 (permalink) Old 12-26-2010, 11:49 AM
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I have a P0420 that comes on and goes off from time to time as well. It's not affecting the way the car runs or drives. I've replaced both front o2 sensors. Eventually I'm going to do the high flow cats and true dual so I'm not too concerned with it. The light just pops on every once in a while.

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post #15 of 18 (permalink) Old 01-04-2011, 10:02 AM Thread Starter
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O.K., I took my T-Bird up to a Monro Muffler & Brake store to have the converter/O2 sensor issue checked-out more in-depth (they said it would be no charge for that) than AutoZone could by just bringing their scan tool out and hooking it up to my car, and guess what? They said my converters and O2 sensors are functioning normally! My "Service Engine Soon" light has been out for at least a week now, and they said there aren't any codes stored in the memory (although, that's probably due to the fact I disconnected the battery this past weekend when I replaced my ignition & multi-function switches).

When I was there, I also had them find the cause of an oil leak I've had for almost a month now; a leak that has gotten substantially worse over the last few days - it's my oil pressure switch. I am currently waiting at home for my local L/M dealer to call me and say they have the new Motorcraft oil pressure switch in and then I'm taking it back up to Monro where they said they'll install it for me for only $35.00 - a bargain for me, considering my work schedule (this just happens to be a slow week and I came home last night and don't have another delivery until Thursday!) and the fact I can't work on cars here at my apt complex!

Dennis
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post #16 of 18 (permalink) Old 01-04-2011, 03:05 PM
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Whoa, wait a minute here!!! Replacing the oil pressure sending unit is such an easy job why on Earth would you pay someone $35 to do it? It's easier to do than an oil change! While you are at it you could follow these simple instructions to make the oil pressure sending unit actually report the real pressure and not just be a dummy switch.

http://forums.tccoa.com/showthread.p...19#post1336719

It's such a quick fix that I doubt the apt. manager would notice and if you're that worried you can go somewhere else and spend the 10 minutes to swap out the sensors.

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post #17 of 18 (permalink) Old 01-04-2011, 03:23 PM Thread Starter
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Quote:
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Whoa, wait a minute here!!! Replacing the oil pressure sending unit is such an easy job why on Earth would you pay someone $35 to do it? It's easier to do than an oil change! While you are at it you could follow these simple instructions to make the oil pressure sending unit actually report the real pressure and not just be a dummy switch.

http://forums.tccoa.com/showthread.p...19#post1336719

It's such a quick fix that I doubt the apt. manager would notice and if you're that worried you can go somewhere else and spend the 10 minutes to swap out the sensors.
I also have time issues due to my job as a tractor-trailer driver for Nestle USA's private fleet; I'm rarely home during the week and I'm usually far too tired on the weekends to have to work on my car. I'd rather spend the time with my wife, or doing other things at home that I let pile-up (I have rather, shall we say, poor time-management skills)! It's kind of a fluke that I'm even home today and, wouldn't you know it, I thought I was going to be home until Thursday and now it turns out I have to be in Gouldsboro, PA at 10:30 a.m. tomorrow morning (a 6.25 hour drive from my terminal in Streetsboro, OH, which is itself about 40 minutes away from where I live in Cleveland, OH!) - so, I won't be getting any sleep again tonight!

Anyway, the switch has been replaced and no more oil leak (it was leaking pretty bad)! And, unfortunately, it turns out my converters apparently ARE bad after all! My "Service Engine Soon" light came on again on my way back up to Monro and the guy who worked on my car used a device that measures temperature and he said there should've been a nearly 100 degree difference in temperatures between the inlet and outlet of the two upstream (front) converters and there wasn't - the readings were nearly identical. He said the larger downstream converter was O.K., but the upstream ones were bad. Oh well, I always did want to replace my O2 sensors and my converter assembly ever since I've had the car (just due to age), so now I have a legitimate reason to! I'm going to get that DynoMax cat-back exhaust system they make for our cars at that time, too.

But, first I have a transmission and new torque converter to get installed, so the exhaust will be my next project!

Dennis
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post #18 of 18 (permalink) Old 01-04-2011, 03:25 PM Thread Starter
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Quote:
Originally Posted by V8ThunderCat View Post
While you are at it you could follow these simple instructions to make the oil pressure sending unit actually report the real pressure and not just be a dummy switch.

http://forums.tccoa.com/showthread.p...19#post1336719
My '97 T-Bird doesn't have an oil pressure gauge; the cluster is different than '94-'97 T-Birds/Cougars.

Dennis
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