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Old 06-09-2011, 08:30 PM   #11
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I replaced the vacum line again it had pretty much melted to the alternator ran it away far enough from the alternator and */c so i wont have that problem again I listened to the cat it has a slight raddle so more then likey the cat has gone out again
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Old 06-09-2011, 11:36 PM   #12
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Quote:
Originally Posted by texasssei View Post
I listened to the cat it has a slight raddle so more then likey the cat has gone out again
Unfortunately. Time for you (or your favorite shop) to break out the welding equipment.

DTC P0420, "Catalyst System Efficiency Below Threshold" means that your catalytic converter is doing a poor job of breaking down the ozone-depleting and smog-generating molecules in your exhaust. Thus, you won't pass your state'* emissions testing while this code is set.

Rarely, it can mean that your downstream (post-cat) O2 sensor has gotten tired, but since you've replaced both, that rules that out.

This is where we would normally suggest that you check for exhaust leaks, but if your cat is rattling, that'* a telltale sign that its internals are in pieces.
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Old 06-14-2011, 02:23 PM   #13
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taking it today to have it changed was gonna do it my self but i dont feel like trying to welding it in this heat
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Old 06-18-2011, 10:11 PM   #14
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alright so i had the cat changed ran it about 150 miles and the ses light came back on same code p0420
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Old 06-18-2011, 11:50 PM   #15
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Was the computer reset after your cat replaced?
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Old 06-21-2011, 05:51 PM   #16
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they said they did but so i un hooked the battey for 30 mins pulled the pcm fuses and let it sit it hasnt come back on i just cant get the evap ready its self so i can get inspected
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Old 06-21-2011, 06:27 PM   #17
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if thats the only code, it may pass anyway, after 2000 is one code not ready still passes in ny. maybe the same for you.

before 2000 you can have two here
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Old 06-23-2011, 09:23 PM   #18
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i just read that you can have one not ready and pass
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Old 08-03-2011, 11:53 PM   #19
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Quote:
Originally Posted by texasssei View Post
cant a damaged vacum line that runs under the */c snout cause the p0420 code to come up
I know i'm jumping on the bandwagon pretty late on this one, but i still want to throw my two cents in. If you have a vacuum line that'* been leaking for quite a while, it could very possibly have damaged the catalyst (P0420). When you have a vacuum leak, the oxygen sensor starts seeing an excessive amount of oxygen in the exhaust stream- looking at live data will show that. When the ECM/PCM sees the oxygen sensor going low voltage, or lean, because of excessive oxygen, it richens the fuel mixture. That can also be observed in live data by looking at the short term and long term fuel trim.

If the system has been over-fueling because of a vacuum leak over a long period of time, the catalyst is working harder to burn unnecessary raw fuel coming down the line and could prematurely fail.
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