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John Krupa
Dodge Dakota
9/10/2001
17:38:25
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 Subject: Error Code P0420
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Message:
Hello All -
had to change the CAT on my 98 dakota - had it replaced by a muffler shop, had over 90,000 miles so dodge wouldn't cover it. A couple of days after replacement, the check engine light appeared, borrowed a obdII scanner and found the error code was P0420 (Catalyst 1/1 Effciency below required level) What monitors this reading? Is it the 02 sensors??? Any help would be appreciated.
Thanks
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Dan Gruber
Gen III
9/10/2001
18:43:09
|  RE: Error Code P0420
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Message:
One of two things is going on. Either your O2 sensors are bad or the new cat is not doing its job.
The O2 sensors monitor the oxygen content of the exhaust both before and after the cat. The cat is supposed to absorb excess oxygen from lean conditions to oxidize the HC and CO also present in the exhaust. This chemical reaction (oxidation) is why the downstream O2 sensor should see less oxygen than the upstream sensor if the cat is good. If the downstream sensor sees the same amount or only a little less oxygen as the upstream sensor, then the cat is not storing oxygen for oxidation with the HC and CO...in other words the cat isn't working. It takes time for this to trip a code...how much time will vary depending on the vehicle and the conditions it's being driven in. This explains why it took a few days for the light to come on the dashboard.
My guess is that one or both of the O2 sensors are bad, perhaps damaged during the cat replacement. Check the wiring to the sensors as well...maybe they were not plugged back in or a wire was damaged. And if you change the sensors, be sure to clear the code using the scan tool.
Dan
2000 CC SLT 4.7 4X4 Auto 3.55 LSD
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Rascal
Dodge Dakota
9/10/2001
18:50:39
| RE: Error Code P0420
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Message:
Dan, you are the MAN! Good info!
Thanks!
Rascal
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John Krupa
Dodge Dakota
9/10/2001
20:13:10
| RE: Error Code P0420
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Message:
Dan -
Thanks for the info
John
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dropt98dakota
Dodge Dakota
9/11/2001
08:41:59
| RE: Error Code P0420
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Message:
about your cat no being warantee I'm not sure about the states but in canada there is a federal law that warantees emissions control equipment like the cat and pcm for 8 yrs 100Km , I just got mine done about a month ago.
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Bruce P
Dodge Dakota
9/12/2001
19:02:23
| Warantee on CAT
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Message:
Not sure about the 1998 but on my 2000 Dakota has a 10-year / 100,000-mile warantee on ALL!! emmissions equipment. This is a FEDERAL LAW.
It used to be 5/50 for many years but you may want to check your 1998 doccumentation that came with your Dakota. (Usually in glovebox)
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PawsPickUp
Dodge Dakota
JOIN HERE
7/08/2016
18:38:47
| RE: Error Code P0420
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Message:
Browsing around for info on my CAT
Noticed the time and date of ur post
dropt98dakota
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