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my12by60

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Discussion starter · #1 ·
I am continuing to catch up on any deferred maintenance on my wife's 1998 Durango (5.2L, 115,000 miles). I have fresh oil/filter, new air filter and I just replaced the original PCV. The P0420 has been coming on and off for the past 10,000 miles or so and it just popped back on this weekend. The truck runs well and we have not noticed any fuel economy problems. After searching and reading here, it seems like changing the oxygen sensors might be a good idea since they are the factory originals and since we have the p0420 code. The Denso front and rear from Rock Auto can be shipped to my door for a total of $78.

Any argument against replacing the sensors after 14 years and 115,000 miles?

I see many here that seem to routinely replace them at 100K miles.

Any common problems or difficulties that I might encounter when taking out the old sensors?

The truck has spent its entire life in the AZ desert (Phoenix area) so rust should not be a problem. I found their location (front after the Y and rear after the cat) and it looks like I should be able to get a wrench on each one.

Are these likely to be really hard to break loose or do most just come right out?

Do the incoming wires connect to the sensors with a cap like a spark plug wire goes on a spark plug?

Please excuse the simplistic questions but I have not changed these before and I don't want to pull or twist anything the wrong way.

When I change the sensors I will also take a rubber mallet to the cat to see if that shakes anything loose and makes the code go away.
 
#2 ·
the wires are hardmount. no way to move them.
the way i did mine was to just cut the top of the old one off, stick a normal socket on it and yank the hell out of it after heating. then i put the new one in with a buttload of neversieze and a normal wrench then i put what you call a crows foot on it and snugged it up
 
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#3 ·
my12by60 said:
Any argument against replacing the sensors after 14 years and 115,000 miles?
Click to expand...
Nope.


my12by60 said:
Any common problems or difficulties that I might encounter when taking out the old sensors?
Click to expand...
Other then busted knuckles and dirty forearms, its a pretty easy job.


my12by60 said:
Are these likely to be really hard to break loose or do most just come right out?
Click to expand...
Its a crap shoot.


my12by60 said:
Do the incoming wires connect to the sensors with a cap like a spark plug wire goes on a spark plug?
Click to expand...
Should just be a male/female connector type thing. clip off and clip on.


my12by60 said:
When I change the sensors I will also take a rubber mallet to the cat to see if that shakes anything loose and makes the code go away.
Click to expand...
Good luck with that…
 
Discussion starter · #4 ·
I received the new oxygen sensors from Rock Auto on Friday and installed them on Sunday. The rear sensor was a bit tough to break loose, but other than that the job was pretty simple. I also took some rubber mallet whacks at the cat to see if that helps break anything loose. I took off the battery cable to reset the computer. The check engine light is now off with just an engine start and idle run. After we put on some drive time, if the P0420 code pops back on again what is my next logical step to solve the problem? A new cat?
 
Discussion starter · #7 ·
Put some miles on the Durango today. Check engine light remains off. Exhaust initially smelled like something was burning -- could be from those mallet raps on the cat. Exhaust smells normal now. Problem may be solved with the new oxygen sensors.
 
#8 ·
Contrary to what you will read on the internet oxygen sensors are almost never the cause for a catalytic converter code, sure it happens but it is very rare, if anything old oxygen sensors can prevent a catalytic code from setting if the cat is failing. I posted the reasoning behind it here a while ago.

The cat code will take a while to come back if it is indeed a problem, the pcm needs to run the cat test 2 times and have it fail 2 consecutive times before it will turn on the check engine light adn depending on your driving habits this could take a month especially if all you are doing is running around town with the vehicle...hope you get lucky
 
#9 ·
I've had the same code on my truck for a while now. It goes off once in a while, but it only stays off for a little a few days to a week at the very most. I got the check engine light checked and that code came up, but AutoZone listed 4 possible causes for the code. Whenever the code goes off my truck starts kind of rough, in addition to that I've been getting what sounds like backfiring once in a while when I rev it or when I get off the gas to slow down and then accelerate right after. I also smell antifreeze sometimes when I'm driving and I know my radiator is full. I think it may be affecting my gas mileage a little bit because right now I'm averaging 13.8mpg according to my overhead computer thingy.

The 4 possibilities were:
1.) Catalytic converter defective (failure possibly due to #2, 3, or 4)
2.) Engine misfire or running condition
3.) Large Vacuum leak
4.) Engine oil leakage into exhaust-valve guide seals or piston rings

If anyone knows what it might be and how to solve all those problems then I'm all ears.
 
#10 ·
Dan R/T said:
I've had the same code on my truck for a while now. It goes off once in a while, but it only stays off for a little a few days to a week at the very most. I got the check engine light checked and that code came up, but AutoZone listed 4 possible causes for the code. Whenever the code goes off my truck starts kind of rough, in addition to that I've been getting what sounds like backfiring once in a while when I rev it or when I get off the gas to slow down and then accelerate right after. I also smell antifreeze sometimes when I'm driving and I know my radiator is full. I think it may be affecting my gas mileage a little bit because right now I'm averaging 13.8mpg according to my overhead computer thingy.

The 4 possibilities were:
1.) Catalytic converter defective (failure possibly due to #2, 3, or 4)
2.) Engine misfire or running condition
3.) Large Vacuum leak
4.) Engine oil leakage into exhaust-valve guide seals or piston rings

If anyone knows what it might be and how to solve all those problems then I'm all ears.
Click to expand...
Bad o2 sensor or your cat's clogged, both easy fixes.
 
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#11 ·
I got my whole exhaust redone only 2 years ago, which included 2 brand new cats. What causes cats to go bad that quick? So those are the reasons that my truck is running like crap sometimes?
 
#12 ·
If the cats are new then I'd definately think about changing the o2s. The cats clog up with soot over time, not in two years though.
 
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#13 ·
l1tech said:
Contrary to what you will read on the internet oxygen sensors are almost never the cause for a catalytic converter code, sure it happens but it is very rare, if anything old oxygen sensors can prevent a catalytic code from setting if the cat is failing. I posted the reasoning behind it here a while ago.

The cat code will take a while to come back if it is indeed a problem, the pcm needs to run the cat test 2 times and have it fail 2 consecutive times before it will turn on the check engine light adn depending on your driving habits this could take a month especially if all you are doing is running around town with the vehicle...hope you get lucky
Click to expand...
But if the above is true, then how could it be the O2 sensors?
 
#14 ·
Dan R/T

My scenario assumes that the vehicle is running properly..yours is obviously not and before any catalytic converter code can be properly diagnosed the vehicle has to be in good running condition.

You got the cats redone 2 years ago...I'm going to assume that you had some "high flow" cats installed...these typically have a very short life span and even shorter if they have to work hard becasue the vehicle is not in proper tune.

Do you have other codes other than a P0420 stored in the pcm.
 
#15 ·
l1tech said:
Dan R/T

My scenario assumes that the vehicle is running properly..yours is obviously not and before any catalytic converter code can be properly diagnosed the vehicle has to be in good running condition.

You got the cats redone 2 years ago...I'm going to assume that you had some "high flow" cats installed...these typically have a very short life span and even shorter if they have to work hard becasue the vehicle is not in proper tune.

Do you have other codes other than a P0420 stored in the pcm.
Click to expand...
I guess that the exhaust shop installed high flow cats, but I don't know for sure. When I redo my exhaust in the Spring I want to ditch the cats and get those cat simulator thingies. I'm trying to get my truck running right before I start adding all the performance parts I just started buying. That code was the only one that came up.
 
#16 ·
It's not only a cat code, an o2 sensor that is not working right can produce the same code.
 
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#17 ·
I'll check into it more thoroughly soon.
 
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Dan R/T
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