Check engine code P0420
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Freshman User
Joined: Nov 2000
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From: USA
Check engine code P0420
Anyone out there familiar with this code? Book says "catalyst system efficiency below threshhold (Bank 1)"
Is it just based on mileage or an actual bad O2 sensor or other bad system component?
Thanks!
Is it just based on mileage or an actual bad O2 sensor or other bad system component?
Thanks!
New User
Joined: Jul 2003
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Check engine code P0420
I have a 96 explorer and i also have the same code coming up, is your vehicle running rough or stalling at all? Ford is stating that i need to have a new catalytic converter put in, but first i would check to see that you O2 sensors and your ERG valve and sensor is operating properly.
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Freshman User
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From: USA
Check engine code P0420
Just got blown back to my hometown after spending the weekend with "Claudette" in the gulf, and have driven over 1,000 miles since last Thursday. Check engine light just lit on about the last 100 miles home. Same code. I talked to a good friend who happens to be a great Ford tech, and he said nearly the same thing. Change O2 sensor first, and if the light comes back then a cat is required. Mine does not stall, but does have a little "hiccup" when you step on the pedal. Ran some 3M cleaner (they make Fords' injector cleaner) through it and it did not make a dramatic difference. Some high tech on that obdII stuff and the Ford ECM. Let's see, uh first throw a sensor at it and if it doesn't get better then throw this really expensive part at it and hope it works. 
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Check engine code P0420
My light has been on for about 2 weeks now, Ask your friend which O2 sensor should be changed? Is it the one before the cat or after, I am actually being told that there are 3 O2 sensors in my explorer, I am thinking that i should just replace the 2 that i know about anyway. I will let you know what kind of results i get.
Elder User
Joined: Aug 2001
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From: South Texas
Check engine code P0420
The code is telling you that the sensor downstream of the cat (after) is reading out of bounds. BUT (and this is a big but) if one of the upstream sensors is bad causing an extreemly rich mixture on one bank or the other, the cat cannot scrub everything out of the exhaust and will cause the downstream sensor to read out of bounds also. You really need to have the system scanned in real time mode to see the O2 sensor outputs in operation to properly determine which one / or what is wrong. A simple code reading will not do in this case, unless you just want to throw money at the problem and change all O2 sensors and cat too.
Dialtone
Dialtone
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Joined: Aug 2001
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From: South Texas
Check engine code P0420
Any dealer service dept or other auto mechanic with the proper equipment and skills should be able to get this for you (at a charge of course). If they act like they do not know what you are talking about, turn and promptly leave. Should be a good indication as to their level of competence.
Here is a web page with a sample screenshot for a scan tool that hooks up to a laptop or other PC http://www.obd-2.com/o2g.htm
There are several companies offering these and other similar interfaces that hook up to Palm style devices along with the associated interface software. Do an e-bay (or Google) search on "OBD2" for some other examples.
Dialtone
Here is a web page with a sample screenshot for a scan tool that hooks up to a laptop or other PC http://www.obd-2.com/o2g.htm
There are several companies offering these and other similar interfaces that hook up to Palm style devices along with the associated interface software. Do an e-bay (or Google) search on "OBD2" for some other examples.
Dialtone
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New User
Joined: Jul 2003
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From: Georgia
Check engine code P0420
I just recently bought a 97 Explorer. Took it to a shop to have a diagnostic ran on it and it came back with nothing wrong. Now a week later, the check engine light has come on. Had it checked out again and the reading came back catalytic system efficiency below threshold. I saw this post and was wondering if anyone has tried any of the suggestions posted? If so, what was the outcome?
Kisha
Kisha
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Freshman User
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From: USA
Check engine code P0420
This is why I made the comment about the "high technology."
If the ECM is so good, why does it not have the ability to discern WHICH sensor is out of range? Really makes no sense!
If the ECM is so good, why does it not have the ability to discern WHICH sensor is out of range? Really makes no sense!
New User
Joined: Jul 2003
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Check engine code P0420
I still have the check engine light on, replaced both oxygen sensors and still no luck, vehicle continues to stall out periodically. As for the suggestion of having someone or dealer read it in real time mode, they stated that they have no idea what i am talking about. I have ordered a new catalytic converter and should have it in about a week. If this does not solve the problem, then just have to keep looking i guess, cant let this problem defeat me.
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Joined: Jul 2003
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Check engine code P0420
Do yourselves a favor and do what the Mustang boys do.
Purchase MIL Eliminators for $20. If you aren't familiar with them, you can read about them here:
http://www.ponyexpressperformance.co...iminators.html
The product keeps the check engine light off for the P0420 code when you remove the cats, your cats or shot, or you gut your cats.
Purchase MIL Eliminators for $20. If you aren't familiar with them, you can read about them here:
http://www.ponyexpressperformance.co...iminators.html
The product keeps the check engine light off for the P0420 code when you remove the cats, your cats or shot, or you gut your cats.
Junior User
Joined: Aug 2003
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From: Monterey
Sorry to the board moderators, I posted a situation related to this topic just a second ago. My bad. I'll remember to use the "SEARCH" in the future.
Anyways, I have the same code P0420 show up on my Superchip module when I ran the diagnostic mode (which I do monthly to see what gremlin is lurking). I have a 97 Explorer V8 AWD. I never saw the check engine flash in any shape or form. The Explorer runs like a champ with no hesitation or stall efforts. It does have 106,000 miles on it. Would appreciate any info on folks who encountered this problem and to hear about any results if you changed the O2 sensors and or cats.
thanks again.
Anyways, I have the same code P0420 show up on my Superchip module when I ran the diagnostic mode (which I do monthly to see what gremlin is lurking). I have a 97 Explorer V8 AWD. I never saw the check engine flash in any shape or form. The Explorer runs like a champ with no hesitation or stall efforts. It does have 106,000 miles on it. Would appreciate any info on folks who encountered this problem and to hear about any results if you changed the O2 sensors and or cats.
thanks again.
New User
Joined: Sep 2004
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P0420 Code Stumper
On a 96 F150 4.9L 6 cyl "Y" code engine there are only 3 O2 sensors. One on each bank of exhaust pipes and one just before the Cat. There are none after the Cat (Why? I have no idea. There should be one aft of the Cat). Check your EGR valve for carbon deposits which could be keeping it from closing fully and causing your stalls. Also run a bottle of RXP through your tank to remove carbon build-up. This should help. Let me know if someone else has found other cures for this problem.
Thanks.
Thanks.
Junior User
Joined: Mar 2003
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P0420 code 96 f150, 130,xxx miles, truck runs good, no hesatation or stalling, this code has been on for awhile, and I gotta smog soon. Only symtom other than check engine light is **** poor fuel economy. +/-12 mpg on a 4.9...not good. Probably gonna take it to a mechanic if I can get a good refrence in the area.