catalyst monitor incomplete
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catalyst monitor incomplete
Looking for some advice
Bought a 97 f150 4.6l 4x4 and resolved some problems which included a bad water pump and a misfire on cylinder 8 p0308.
I have driven the truck over 500 miles since clearing the MIL codes and still have a catalyst monitor incomplete condition.I have followed the Ford drive cycle script and even changed down stream O2 sensors.
Anyone have a suggestion on getting the catalyst monitor test to set or at least indicate why it is not completing.
Bought a 97 f150 4.6l 4x4 and resolved some problems which included a bad water pump and a misfire on cylinder 8 p0308.
I have driven the truck over 500 miles since clearing the MIL codes and still have a catalyst monitor incomplete condition.I have followed the Ford drive cycle script and even changed down stream O2 sensors.
Anyone have a suggestion on getting the catalyst monitor test to set or at least indicate why it is not completing.
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Joined: Jul 2004
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From: Easton, Pa.
Do you now have a code 420?
If yes, there is cat failure.
This monitor does not take very long to complete because it is only a ratio test between the front and rear OX sensor switching.
If you don't see it right away after a couple drive cycles, the computer ignors it and turns the monitor off but does not clear the code because the signal is of no further value once the failure is detected and not cleared..
If you look at the sensor live data with a good scanner you will see either the switching values are not correct or zero reading showing it was abandon.
Only way to get them active again is to do a clear of the code, then let the system go after it again, then take another look with a scanner.
Good luck.
If yes, there is cat failure.
This monitor does not take very long to complete because it is only a ratio test between the front and rear OX sensor switching.
If you don't see it right away after a couple drive cycles, the computer ignors it and turns the monitor off but does not clear the code because the signal is of no further value once the failure is detected and not cleared..
If you look at the sensor live data with a good scanner you will see either the switching values are not correct or zero reading showing it was abandon.
Only way to get them active again is to do a clear of the code, then let the system go after it again, then take another look with a scanner.
Good luck.
Last edited by Bluegrass; Dec 24, 2011 at 02:33 PM.
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Still no MIL DTC codes and catalyst monitor is incomplete.I was able to get a waiver to buy plates because money spent on O2 sensors and various other parts reached a state limit.
I watched the O2 readings on my scanner and they appeared valid but I can not read $06 codes which I understand can give a better picture of what is going on with the system.
I might try pulling the battery cables to reset the ecu and see if the monitors clear.
I watched the O2 readings on my scanner and they appeared valid but I can not read $06 codes which I understand can give a better picture of what is going on with the system.
I might try pulling the battery cables to reset the ecu and see if the monitors clear.
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Joined: Jul 2004
Posts: 6,200
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From: Easton, Pa.
Here is the deal about the cat monitor.
The PCM test looks at the switching 'ratio' between the front and the rear sensors. If it is too often or not often enough it is a measure of oxygen storage in the cats or possibly slow sensor response.
If the cats are nearing end of life they will never clear the test and may be marginal at this time depending on temperature they are operating at.
I would look at the temp differences between each side and front to rear cats to see if an obvious difference is seen.
It is with the cats no where else.
This is the designed in diagnostics the system has been given or you would never have a way to know anything is going bad.
Good luck.
The PCM test looks at the switching 'ratio' between the front and the rear sensors. If it is too often or not often enough it is a measure of oxygen storage in the cats or possibly slow sensor response.
If the cats are nearing end of life they will never clear the test and may be marginal at this time depending on temperature they are operating at.
I would look at the temp differences between each side and front to rear cats to see if an obvious difference is seen.
It is with the cats no where else.
This is the designed in diagnostics the system has been given or you would never have a way to know anything is going bad.
Good luck.
Senior Member
Joined: Jul 2004
Posts: 6,200
Likes: 39
From: Easton, Pa.
Good for you.
My thinking is the cats were contaminated for some reason and the length of run time has burned the contamination off enough to raise their oxygen storage level just enough to pass the PCM test program.
Good luck.
My thinking is the cats were contaminated for some reason and the length of run time has burned the contamination off enough to raise their oxygen storage level just enough to pass the PCM test program.
Good luck.
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After you fixed the issue.... assuming it was the O2 sensors the computer will continue to show the issue for 3 drive cycles with no faults according to my book and then reset itself. I am currently having a major issue with my truck and it sounds like it's along the same lines except my truck won't even start. If anyone has advice on my problem please check out my thread "help" as I also need help.