Tech wrote:just search for the P0463, you'll find TONS....including at least a couple how-to's.

The front "02" on R51's isn't an 02, it's an A/F sensor, which works on completely different voltages than the conventional 02. As long as you don't mess with the primary cat between the a/f and rear 02, you can do whatever you want to the rear cats. You don't even really need to worry about keeping B1 and B2 balanced. The injectors aren't batch, but sequential. The ECM will take care of it. If you bust out the matrix from the cat, make sure you do a COMPLETE job. The broken down material can get sucked UPSTREAM ( believe it) and turn your engine into an oil burner.

Do you know what the voltages are and is this a good indicator of whether or not the sensors are bad if the readings are off?

disallow wrote:

skwerl wrote: The article states there are 4 cats on an '05 are you saying their is only one primary and two secondaries?

It has some good info on how to test the cats if you have an infrared thermometer. I may try that but I still plan on taking them off anyway to try and look at the honeycombs.

You say not to mess with the primary cat between the AF and O2 sensors. I assume you mean not to remove the honeycomb inside the cat, right? Since it has to function and give correct readings between the AF and O2 sensors. If that one is bad, I'm pretty much going to have to buy a new one. What's the chance it's just a bad AF or O2 sensor?

There are 4 cats, 1 between the FA and O2 sensors on each bank, and 1 after the O2 sensors on each bank. I think they just clean the exhaust more.

A bad O2 sensor (post cat) shouldn't have any effect on how the engine runs. It just monitors the performance of the CAT and flicks on a code if its not.

I replaced my FA sensors last summer to see if it would help my fuel economy. The voltages read from my Cortex were exactly the same after I replaced them. I got better fuel economy for about 3 months, then back to the same $#|tty mileage.

I'll probably get the ECM relay replaced at the dealer, check my spark plugs, do the vacuum test, and test the AF/O2 sensors if they can be tested. Then move to inspecting the cats last.

Out of curiosity, what's your temperature range where you live? A span of three months, if you're temps were getting much colder it would probably be a contributor to worse fuel economy. In summer here I can get 22-23mpg highway (using the on-board gauge) and only 20-21 tops in winter due to the denser air and worse wind resistance.

I just remembered, my wife was low on gas one day and accidentally put about 1/2 gallon of 2 cycle gas to get her to the gas station but that was several weeks ago. I wonder if that could've caused plug or sensor fouling? From what I've read, that little amount of 2 cycle gas driven for a short time then being diluted heavily after a gas station stop shouldn't ruin cats. That maybe could explain why both codes tripped at once. I got the codes reset and ran some gumout injector or fuel cleaner through on the next fill-up but the codes tripped again a day or two later.

skwerl wrote:Do you know what the voltages are and is this a good indicator of whether or not the sensors are bad if the readings are off?

I had posted an article on the board some time ago that showed good voltages. basically, the lower the better. should go to 0.3V when in closed loop.

skwerl wrote:I'll probably get the ECM relay replaced at the dealer, check my spark plugs, do the vacuum test, and test the AF/O2 sensors if they can be tested. Then move to inspecting the cats last.

Out of curiosity, what's your temperature range where you live? A span of three months, if you're temps were getting much colder it would probably be a contributor to worse fuel economy. In summer here I can get 22-23mpg highway (using the on-board gauge) and only 20-21 tops in winter due to the denser air and worse wind resistance.

Its bloody cold here, today was -40F with the windchill. But even before it got cold, I was back to getting 225km (140mi) on 40L (10.5USG), or 13.3 MPG. Mostly highway. I used to get 350km (217mi) on the same amount of fuel, or 21 MPG. No OBD codes, no engine issues, great power. Not sure what to do, but as long as it runs good I guess I'm ok, its not our primary vehicle.

skwerl wrote:I just remembered, my wife was low on gas one day and accidentally put about 1/2 gallon of 2 cycle gas to get her to the gas station but that was several weeks ago. I wonder if that could've caused plug or sensor fouling? From what I've read, that little amount of 2 cycle gas driven for a short time then being diluted heavily after a gas station stop shouldn't ruin cats. That maybe could explain why both codes tripped at once. I got the codes reset and ran some gumout injector or fuel cleaner through on the next fill-up but the codes tripped again a day or two later.

You are correct, this shouldn't be any concern.

I should also clarify that although mostly highway, we also do a tonne of short highway trips, my wife dropping dd off at preschool, idling the truck, etc etc. But its still way worse than it should be.

I would to the ECM relay (should be free to you) and get them to check the ECM for codes - your misfire should be stored along with the cat code. Maybe play dumb and don't mention the 2-stroke stuff. Anything that causes a miss-fire, weither ECM relay or bad fuel (often diesel...I know..., but I see it a couple times every year...) can kill a cat quick. Thats the only reason a MIL flashes. If they see a code and you push them gently, you may be able to get them to cover it by virtue of the ECM relay causing miss-fire, causing cat damage. They can also test for cat efficiency without disassembly, and re-run the SRT monitors after clearing the code. If the cat monitor completes without a fault - you SHOULD be ok. Also listen for a cat-rattle when cold. If worse comes to worse, ask them to apply for good-will, you'll likely end up paying 1/3.

Tech wrote:I would to the ECM relay (should be free to you) and get them to check the ECM for codes - your misfire should be stored along with the cat code. Maybe play dumb and don't mention the 2-stroke stuff. Anything that causes a miss-fire, weither ECM relay or bad fuel (often diesel...I know..., but I see it a couple times every year...) can kill a cat quick. Thats the only reason a MIL flashes. If they see a code and you push them gently, you may be able to get them to cover it by virtue of the ECM relay causing miss-fire, causing cat damage. They can also test for cat efficiency without disassembly, and re-run the SRT monitors after clearing the code. If the cat monitor completes without a fault - you SHOULD be ok. Also listen for a cat-rattle when cold. If worse comes to worse, ask them to apply for good-will, you'll likely end up paying 1/3.

I'm definitely going to have the ECM fixed. It's free of charge and there is no time limit I was told. The warning went off after work today so I'm hoping it may just be that I've gotten the bad gas finally flushed out and the heat has maybe finally burned all the oil off. I know the light usually goes off for a while and comes back on but I hope I'm OK now.

I always play dumb

Hi guys, I would like to try the non fouler trick...but I don't know which one to buy and where to get it from. can you help me out with that?? thanks!!

You can get anti-foulers from any auto parts store, or you can just get the O2 extenders:

http://www.bigdaddiesgarage.com/straight-cel-fix.html

thanks for the help. how many do I need to get??

Two....one for each rear O2 sensor.

Het tech - you seem to know a lot about the pathfinders. My cats failed and now I burn about 1qt every 800 to 1000 miles. When the substrate gets sucked back into the cylinders does it score the cylinder walls ? Is there something I can do short of a complete rebuild ?

I ordered 2 and they will be here on the 23rd. thanks for your help.

Not to bring a dead post back to life but I think it holds valuable info. I have an 05 pathfinder. The SES light came on, had the code checked it was P0430. Catalyst system efficiency below threshold - bank 2
Probable cause:
1. Large vacuum leak
2. Fuel system fault
3. Ignition system fault
4. Failed bank 2 catalytic converter
So I took it to an exhaust mechanic that check the actual O2 sensor. The only problem/issue with it was that it was running hotter than its threshold bc of the motor overworking due to the initial signs of the transmission failure.

So to sum it up, the 0430 code in my situation wasn't the catalyst system needing to be replaced but the transmission was causing the motor to overwork. So now I get to have the transmission rebuilt and get a new radiator.

Well, that sucks!... But good information!

Jime wrote:So to sum it up, the 0430 code in my situation wasn't the catalyst system needing to be replaced but the transmission was causing the motor to overwork. So now I get to have the transmission rebuilt and get a new radiator.

So other than the list of failed components, were there any signs that your transmission was going bad? Maybe:

1. Rough or erratic shifting
2. Dirty or burnt trans fluid
3. Poor fuel economy
4. Funny noises from transmission

I experience #3 on the list, and maybe #2 as well.

t

dumb question - are the o2 sensors widebands on the r51. cause my bully dog shows AFR, i wasnt sure how accurate it is.