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[630 PAC]

I have a 05 Pac... Please give me some insight on P0420 code( autozone readout) per check engine light...details below per autozone printout

Definition
Catalyst efficiency low bank 1

Proable cause

1.. Catalytic converter defective( failure possibly due to #2,3, or 4)

2... Engine misfire or running condition

3... large vacuum leak

4... engine oil leakage into exhaust - valve guide seals, pistonrings

now since I haven't had a tune up since buying the Pac 2yrs ago( dashboard reads 75,000 mi) , if I where to replace the the spark plugs could that correct the issue?

any insight would be helpful

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[Geronimo]

Nope, probably won't help. The car may run better, but the converter has lost its ability to convert the exhaust gases. Most likely cause is an oil burning issue that has coated the converter grid over time. Going through a quart of oil every 800 - 1500 miles? I hear it a lot from  Chrysler owners, and then the dreaded P0420 or P0430 shows up after the damage is done. Might have to bite the bullet and replace the converter. Beware of aftermarket ones that may not be effecient enough to satisfy the computer's self tests. Some companies claim OBDII compliance, but I've installed some on other cars and it would still trigger a code. Also check with Chrysler to see if there is a software update that may make allowance for "normal" engine wear. I know GM has done that in the past, and there may be others.

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[shipman]

Just curious - I wonder what is actually being measured, what kind of sensor in the cat triggers this code?  Is there an oxygen sensor or something in the cat?

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[Geronimo]

Maybe this will help:
http://en.wikipedia.org/wiki/Catalytic_converter

Basically, it cleans whatever pollutants are left in the exhaust. All newer cars, including our Pacifica's have O2 sensors behind the converter just for checking the function of the converter. The engine computer, at certain times, runs it's own self tests to make sure the converter is cleaning the exhaust of pollutants. If it fails the test, your check engine light comes on

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[scottydl]

Cat replacement may eventually be needed, but a tune-up (spark plugs, throttle body cleaning) is a good place to start.  Those items can cause misfires and trip codes sometimes also.  As stated, make sure you are checking and keeping your oil level up in the engine, if oil is burning.  I've never had this problem on my '07 4.0L but I have read about it on older model years.

Here's a write-up with photos on spark plug replacement: http://www.pacificaworld.com/forum/index.php?topic=2055.0

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[Geronimo]

Good suggestions, Scotty. Regular maintenance is key. But since no other codes were mentioned, nor misfires reported, I'm assuming that it's running OK. I would drive it with a scan tool (I use a OTC Genysis EVO) or some other data recording device to check for intermittent misfires and fuel trim issues. Those not withstanding, the only other possible contaminants are oil, coolant, silicone from gasket making material, or fuel additives. We might have to break this down to which engine has the most oil burning issues. The ones I've seen this with are the 3.8's, in Pacifica's and Caravans. Also PCV valve maintenance may come into play here. It would be great if some wiz on this forum came up with a way to chart it, using miles driven per quart, by engine type.
One thing that has impressed me has been the external sealing technology of modern engines. I've seen lots of newer Chrysler's (GM and Fords too) that match the sealing of import engines. Since my Pacifica (05, 3.8, 92,000 miles) is dry as a bone underneath, that quart I put in at 2000 miles had to go somewhere, and we all know where it was. Since I just bought it 2 months ago, I'm going to stay on top of it to monitor oil usage, maybe experiment with 5W30 synthetic to see what happens. It's not a VVT engine, so I'll probably be OK.

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[polito1973]

i have this issue big time , the oil consumption, low mileage , but replacing the converter is an expensive proposition , nearly $900 bucks  any ideas in how to approach this with the dealer or Chrysler?

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