Bob,
I think at thins point, given all the input from those more edumacated than
I, it might be a good idea to get out the book and check the condition of
the O2 sensors. How much is a little oil consumption? I would think it would
have to be significant amount over the relatively short period of time since
you had a new cat installed to affect it. Might not be a bad idea to do a
compression check, wet and dry, as well to give you some more info. One
other question, when AZ pulled the code, you said it the printout they gave
you said Bank 1. When they read the code off the scanner, did they say
anything about sensor 1 or 2? If they did, it would confirm what others have
said it being the post cat O2 sensor. I know when I pulled codes, I always
wrote down which sensor was identified just because some of the codes don't
specify when you pull them up ion the computer.
HTH,
Ray Irons
Dover, DE
-----Original Message-----
From: owner-dakota-truck@bent.twistedbits.net
[mailto:owner-dakota-truck@bent.twistedbits.net]On Behalf Of bob
Sent: Monday, February 21, 2005 7:15 PM
To: dakota-truck-moderator@bent.twistedbits.net
Subject: Re: DML: Trouble code P0420
Ray,
I had the Cat replaced last September for the same reason you replaced yours
(rattling). Could it be a bad O2 sensor? For what it's worth the truck seems
to run
fine so it's probably not a large vacuum leak, although now that you mention
it, it
does seem to be consuming a little oil.
Ray Irons wrote:
> Bob,
> I went and got my little book, which your local Auto Zone store
should have
> done, that list's the all the generic codes, their meaning and probable
> causes for the code. P0420, according to the book I have, says:
>
> P0420 thru P0422
> Catalyst efficiency low bank one
> The oxygen sensors monitor the catalytic converters ability to store
oxygen.
> Probable causes
> 1st. Catalytic converter defective (Failure possibly due to #2,3,or 4)
> 2nd Engine misfire or running condition
> 3rd Large vacuum leak
> 4th Engine oil leakage into exhaust-valve guide seals, piston rings
>
> Either way you go, it would seem you have a bad cat. How many miles do you
> have on the truck? I forget what the limit is but the manufacture has to
> warranty the cat as part of the emission system for, I think, 80K miles
and
> 6 years. IF you are under the mileage, you may be able to get it replaced
at
> the dealer for free. I had mine done a couple of years ago when I heard
> something rattling in the cat when the truck had over 50K miles on it. You
> also need to look at the other items on that list and see if any of them
> apply to your truck. Since you don't mention you had a code pulled for a
> misfire, (they would be P0300, random multiple misfires, P0301, misfire #1
> cylinder, etc.) A misfire doesn't seem likely. A vacuum leak should be
easy
> enough to recognize. I found a troubleshooting guide that gave an easy way
> to find vacuum leaks. With the engine running, take a propane plumbers
torch
> and open the valve but do not light the torch. Aim the nozzle around the
> hoses and intake manifold, wherever you suspect a vacuum leak. When the
> engine RPM picks up, you have probably found the leak. Engine oil leakage
> should also be easy to rule out if you keep a close eye on you oil
> consumption.
>
> Let us know how this turns out for you and what your solution is.
>
> HTH,
>
> Ray Irons,
> Dover, DE
> -----Original Message-----
> From: owner-dakota-truck@bent.twistedbits.net
> [mailto:owner-dakota-truck@bent.twistedbits.net]On Behalf Of bob
> Sent: Sunday, February 20, 2005 4:21 PM
> To: dakota-truck-moderator@bent.twistedbits.net
> Subject: DML: Trouble code P0420
>
> After getting a "CHECK ENGINE LIGHT" I went to Auto Zone and had the
> code pulled. They said it was a P0420. The print out gave the following:
> The PCM has determined that the catalyst system efficiency for Bank 1 is
> below threshold for the current engine operating conditions. (Bank 1
> identifies the location of cylinder #1, while Bank 2 identifies the
> cylinder of the opposite Bank). They were not very helpful in
> identifying possible solutions. Any ideas? Thanks
>
> Bob
> 99 Dakota
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