Honda Odyssey Forum banner

New catalytic converter & o2 sensor. Now EGR? PO420 code? O2 sensors? Any advice?

11K views 27 replies 11 participants last post by  wormguy 
#1 ·
After reading through this forum I understand that my husband and I are definitely not alone when it comes to the problems I'm experiencing with my 2002 Honda Odyssey. But after reading the many posts and varied "solutions" I'm not sure that I know what our next step should be. So, at this point I certainly would appreciate a few opinions.

Here's the history: I have a '02 Honda Odyssey that had the transmisson replaced for failure around 75,000 miles (van has 84,000 on it now). Next, the CEL came on and the codes indicated that the problem was the catalytic converter and the O2 sensor which we had replaced about 2 weeks ago. Within 24 hours after the catalytic converter and O2 sensor was replaced we get another CEL and when I stopped by AutoZone and had them read the code it came up PO420 "Catalyst efficiency below threshold in Bank 1" and the service guy told me it was probably the EGR valve. Well, I had the EGR warranty extension notice sent to me but I never noticed the van having the symptoms they mentioned so I didn't have it serviced. Today on a whim I called Honda and told them my :( sad story and asked if they would still cover my car since it was so close on the mileage and they refused. Not to get off on a tangent - but for goodness sakes, if they know this is an issue why not cover it?!!! I love the van but these problems have been a real issue for us because of the $$$. We don't trust our local dealership because they tried to screw us over on the transmission deal and we ended up having a local tranmission shop do the job. A shop local to us does our work but they don't specialize in Honda's and while we consider them honest I sure would like to know what a few people who've experienced the same issues have to say.

So, EGR has never been replaced. Van does not halt or hesitate but the gas mileage is only 18 mpg. Aside from the gas mileage, there is no other obvious problems I've noted while driving. I did fill the gas tank with Shell's V-Power stuff for the last two fill-ups. I've been wondering if the smartest thing is to replace the EGR and replace the plugs - and what about the "other" O2 sensor? Any suggestions would really be appreciated.
 
See less See more
#2 ·
Plugs aren't due till 105K. What was your previous mileage results, much better than 18? Replacing the EGR may not affect the P0420 code especially since you have non of the typical failure symptoms.

What to do...well change out the other sensor since you've done the other one and installed a new CAT. BTW, are you buying OEM Honda parts? If not, aftermarket sensors have been known to not work...

Good luck!
 
#5 ·
dstockler said:
Thanks for taking the time to reply. Appreciate your opinion.
Do a search on the codes and on the )2 sensers here and read some of the problems others have had on the replacement cat and O2 sensers. Replacement Cats and O2 sensers are not all necessarily created equally...
 
#6 ·
We did purchase the cat converter ourselves after researching online quite a bit. Supposedly the unit we bought was designed to be larger (among other redeeming qualities) and was to keep the engine light off (as compared to other OEM aftermarket CC - according the muffler shop). But after it was installed the wiring on the O2 sensor wasn't long enough to fit and our shop ordered us a new sensor with a longer wire. Is there a way for our shop to check the O2 sensor they installed to know if it's working properly? In the meantime, for what it's worth, I think I will clear the light and see what happens the next time it runs a test. I am on my second tank of Shell's premium gas - for whatever that's worth.

Another thing is, I think the code I originally had actually indicated it was an O2 sensor and that code has not come back on since the CC and O2 sensor was changed- but does this new code also mean it could be the O2 sensor? If so, that's a little confusing to me.

By the way, what does "bank 1" mean?

Thanks to anyone who has time to answer.
 
#7 ·
dstockler said:
We did purchase the cat converter ourselves after researching online quite a bit. Supposedly the unit we bought was designed to be larger (among other redeeming qualities) and was to keep the engine light off (as compared to other OEM aftermarket CC - according the muffler shop). But after it was installed the wiring on the O2 sensor wasn't long enough to fit and our shop ordered us a new sensor with a longer wire. Is there a way for our shop to check the O2 sensor they installed to know if it's working properly? In the meantime, for what it's worth, I think I will clear the light and see what happens the next time it runs a test. I am on my second tank of Shell's premium gas - for whatever that's worth.

Another thing is, I think the code I originally had actually indicated it was an O2 sensor and that code has not come back on since the CC and O2 sensor was changed- but does this new code also mean it could be the O2 sensor? If so, that's a little confusing to me.

By the way, what does "bank 1" mean?

Thanks to anyone who has time to answer.
Bank 1 refers to the 1st O2 sensor closest to the engine between the engine and CAT.
 
#8 · (Edited)
Bank 1 and Bank 2 refer to the front and rear bank of cylanders. However cars with single exhaust have only one O2 senser while cars with dual exhaust have two O2 sensers. Cars with single exhaust will always refer to the primary O2 senser as bank 1 as there is no bank2 O2 senser.

The O2 sensers can be checked with a good OBDII tester and a mechanic knowlegable enough to analyze it. The following article is a good place to start in understanding the problem and making the checks. Graphing the O2 sensers will show how good they are. http://www.troublecodes.net/articles/catfailure/
 
#9 ·
Hi,

Your code P0420 is set off when the 02 sensor that sits AFTER the CAT starts to switch close to the same rate as the one before the cat. Its' mission in life is to make sure that the cat converter is living up to its job of cleaning up the exhaust. Honda sets the tolerance of HC's in the exhaust extremely low. So low that some have posted the code came back after replacing their bad OEM converters with an aftermarket one. I would first erase the code from the computer and see if it comes back. If it does, than I would scan the computer while the vehicle is running to see what the 02 sensors are doing. If your shop has a decent quality scanner then they should be able to do that for you.
 
#12 ·
I have the same issue here,replaced the trans at 80k miles and now the van is popping on the cel with the P0420 code ,it happened 3 month ago ,so i pour some fuel injector cleaner,I cleaned the intake manifold EGR passage and replaced the spark plugs ...it was good for a few months but now I got the CEL with the same P0420 code again...
Im getting tired of this dam CEL every time it gets on, its costing me big $$$$
 
#13 ·
My wife's 2000 with 81000 miles threw a po420. It's six months, 1k miles out of warranty and Honda basically has said tough luck. They want $1400.... I'm going to replace it with an aftermarket direct fit myself when the weather is warmer. But... I'm not a happy customer and plan to let everyone I meet up with know!
I'm the original owner, owner of three Hondas. BTW, I would not have even thought of asking for compensation, if I wasn't just outside of warranty.
 
#14 ·
Ross_t said:
My wife's 2000 with 81000 miles threw a po420. It's six months, 1k miles out of warranty and Honda basically has said tough luck. They want $1400.... I'm going to replace it with an aftermarket direct fit myself when the weather is warmer. But... I'm not a happy customer and plan to let everyone I meet up with know!
I'm the original owner, owner of three Hondas. BTW, I would not have even thought of asking for compensation, if I wasn't just outside of warranty.
I'd be careful about using an aftermarket cat. I just read quite a few other posts here (and have talked to several of my mechanic friends as well) on the subject of non-OEM cats, and the verdict is this: often, if not most-of-the-time, ONLY the OEM cat will fix this issue.

If you want to save some $, go to one of the online Honda dealer parts websites and buy an OEM converter there--think it is around $700 at one place I recently checked.
 
#15 ·
P0420

You are not alone! I started having the code P0420 for about 1 years now. The van ran no different with P0420 on or off. In all case, it turns itself off after driving for awhile. My best case, it turned off after 99 miles and the worse case 1100 miles. It passed emission last year but not so sure this year.
 
#16 ·
Re: P0420

odysseyrules said:
You are not alone! I started having the code P0420 for about 1 years now. The van ran no different with P0420 on or off. In all case, it turns itself off after driving for awhile. My best case, it turned off after 99 miles and the worse case 1100 miles. It passed emission last year but not so sure this year.
If Wisconsin is a OBD II compliant testing State, just make sure the CEL hasn't been on for a few days and it should pass. IL only does the plug in idle test now. It will detect recent resets and fail you so driving for a few days is mandatory prior to testing.
 
#17 · (Edited)
A bad CAT will have zero affect on the drivability of the van. It only means it is poluting the van. Passing or failing the emitions test is just a matter of whether the CEL is on or off at the time of the test.

Resetting the computer reseta all the continuous and non-continuous monitoring tests to not complete. It then takes several drive cycles for them to show complete. If they are not complete you will fail the emetions test. Therefore the van has to be driven for several days before taking the test.
 
#18 ·
William Wiles said:
A bad CAT will have zero affect on the drivability of the van. It only means it is poluting the van. Passing or failing the emitions test is just a matter of whether the CEL is on or off at the time of the test.

Resetting the computer reseta all the continuous and non-continuous monitoring tests to not complete. It then takes several drive cycles for them to show complete. If they are not complete you will fail the emetions test. Therefore the van has to be driven for several days before taking the test.
I don't know about several days . . . I borrowed a scanner and cleared this code on my 2001 as I had to go through emissions in order to transfer the title. Right after clearing the code, I drove the vehicle for about an hour, both highway and city, and then drove to the emissions test station. Passed just fine.
 
#20 ·
William Wiles said:
A bad CAT will have zero affect on the drivability of the van. It only means it is poluting the van. Passing or failing the emitions test is just a matter of whether the CEL is on or off at the time of the test.

Resetting the computer reseta all the continuous and non-continuous monitoring tests to not complete. It then takes several drive cycles for them to show complete. If they are not complete you will fail the emetions test. Therefore the van has to be driven for several days before taking the test.
Bad CAT on Honda's with it's tightly regulated standards will warn owners of exceeding standards while still flowing efficiently. On our old 86' Caravan with a cracked cylinder head and lenient regulation, it allowed driving till the water / coolant vapor destroyed the substrate causing enough blockage to limit a max speed of about 65 mph. The exhaust tone at idle was practically nonexistent too. Revving it up only produced a subdued whoosh of air.
 
#21 ·
I'm new to the forum, but I am extremely impressed with the knowledge of the people in the forum.

In response to the original posting.

I have 183k mi on my Odyssey and have not replaced my o2 sensors, which I probably should change before the failure occurs and starts to adversely affect the catalytic converter. If there are two O2 sensors, I agree with others on this forum to replace both. Your mpg is a little low compared to mine, but may be the difference in how we drive. I am currently getting 24-25 mpg on the highway.

As others stated use the OEM parts. I have used non-OEM parts in the past saving me more than half the price, but have found them to be inadequate for my Honda, Mercedes, and Toyota.

It baffles me on this forum that so many people have such bad costly experiences with their Odyssey. Knock on wood, I am very fortunate since my Odyssey's reliability is phenomenal with me putting forth very little maintenance and repair costs.

Motor Oil - change every 15k mi w/Mobil 1 15k oil.

Trans fluid - Changed only once at 160k mi

Brakes - Front brakes, rotors, and calipers. Can you believe the rear brakes (drums) are still fine?!

Timing belt water pump and spark plugs at 95k mi.
 
#23 ·
williamhaas said:
I'm new to the forum, but I am extremely impressed with the knowledge of the people in the forum.

In response to the original posting.

I have 183k mi on my Odyssey and have not replaced my o2 sensors, which I probably should change before the failure occurs and starts to adversely affect the catalytic converter. If there are two O2 sensors, I agree with others on this forum to replace both. Your mpg is a little low compared to mine, but may be the difference in how we drive. I am currently getting 24-25 mpg on the highway.

As others stated use the OEM parts. I have used non-OEM parts in the past saving me more than half the price, but have found them to be inadequate for my Honda, Mercedes, and Toyota.

It baffles me on this forum that so many people have such bad costly experiences with their Odyssey. Knock on wood, I am very fortunate since my Odyssey's reliability is phenomenal with me putting forth very little maintenance and repair costs.

Motor Oil - change every 15k mi w/Mobil 1 15k oil.

Trans fluid - Changed only once at 160k mi

Brakes - Front brakes, rotors, and calipers. Can you believe the rear brakes (drums) are still fine?!

Timing belt water pump and spark plugs at 95k mi.
Excellent results with the tranny. Do you recall the condition of the fluid before the change regarding color and smell? And did you just drain and fill it with about 4 qts. of fluid? Or was it done several times like the owners manual recommends....3 times plus 1?
 
#24 ·
Response to:
"Excellent results with the tranny. Do you recall the condition of the fluid before the change regarding color and smell? And did you just drain and fill it with about 4 qts. of fluid? Or was it done several times like the owners manual recommends....3 times plus 1?"

I am color blind between red and green. However, my wife said the color was red and there was no burnt smell. So the condition of the old fluid was good. There was very little residue on the drain plug, which I susspect is a good sign as well. I did one drain, and filled it with 3 qts of Honda's fluid.
 
#26 ·
my_dogs_ody said:
Not days...150 miles.

The best way to get to 150 miles is to jack the front of the van (double jack it), start the van, put it in drive and let the wheels roll.

The above is very unsafe....but it will get you to 150, and burn very, very little gas.
A poor and dangerous attempt to set the codes. The procedures are well documented in the Honda OEM service manual. Most entail driving the vehicle in stop and go driving with periods of cruise. The EGR is a little different as it requires driving between 50-62 mph in D for a minimum of 10 seconds, decelerate from 62 mph by completely releasing the accelerator for a minumem of 5 seconds. The simplest way is to just drive it normal for a couple days.



on the 99-00 vans to check for complete you have to use the OBDII scanner. On the 01-04 you can check if they are complete by turning on the ignition without starting the van. The mil will light for 15-20 seconds and go off if the indicators are set. If any are not set the mil will flash 5 times.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top