Pathfinder Catalytic Converter Problems

[Chris.m]

Ok, so about a month ago, I got the p0420 code. Since everything seemed fine, I just asumed it was the downstream sensor which would only need to be replaced when I go through aircare (Canadian emissions test). Anyway, I ignored the SES light for a while until recently when the truck has been really sluggish. The acceleration is nothing like it used to be. My gas milage is a bit below normal,theres no strange sounds, my idle rpm is 750 like it should be, and there is no smell from the exhaust which is supposed to be an indicator or a broken cat. Anyway, the one thing that really got me was a pulsing exhaust ( I read somewhere that that meant the cat was broken). At this point, I'm quite convinced that the problem is the cat, which costs $900 for the part from the dealership. Since I dislike dealerships, I'd prefer to install it myself and try to source it for cheaper. So my question is; are these problems indicators of broken cats? and does anyone know any good web sites that ship to canada and have cheap cats?

P.S. just incase this is my fuel filter clogged and a downstream sensor problem, I'm replacing the filter tomorrow.

[ARKQX33V6]

Check exhaust volume. Catalytic failure should send DTC of O2 sensor post converter. MAF may be blocked. Do a quick compression check. A plugged exhaust anywhere may cause problem. Have you used other fuel additives. What is km driven. Lots of things to check. Try to eliminate 1 at a time. Broken converter maybe, can you remove and test?
r

[Chris.m]

So replacing the fuel filter didn't change anything, I checked the MAF and it was fine. I don't use any additives and the km are 254,000. How do I check exhaust volume? I'm thinking I'll try and take out the resonator on the weekend and try it then, and if I really have the time take out the cat and try it

[ARKQX33V6]

The easiest way is to put an open hand over the exhaust port and feel if at idle the amount of CFM cubic feet per minute seems appropriate for what is happening, then have some one press the gas peddle, does the amount of exhaust rise? This is a preliminary look see and may help you decide if a further look see is needed.

Remember you have a fuel/air coming in, combustion eats up the fuel and 20% of the air and exhaust gets hot from combustion and things expand. If you have a mechanic or garage they can do an exhaust analysis for you that may nail down the problem.

The resonator Nissan used was crap, the outside showed evidence of breaking down, so what do you think is happening inside, it it is collapsing the exhaust takes too long and offers too much back pressure on the system.

Good luck and wear gloves, exhaust is hot and sharp edges are everywhere.

[JEFFP477]

i am having the same issue.. same code bith side p0420 and p0430, i have replace my cats last yr, and now the code is back on, i checked the o2 sensors again, and it is still good, i changed it same time as the new cats all four. my maf is not clogged. and sorry to sound ignorant but where do you measure the pressure again? at the tail pipe ?

and on top of this, my o/d is working, the light does go on when you first start it up, but if you press the o/d button it does nothing.. sorry for jacking the thread...

[jika]

There is a cheap ($5) solution for P420 code. Just google 'spark plug fouler' or check here

another-nico-exclusive-p430-and-p420-codes-t495997.html

2 for each sensor (rear only).

[Chris.m]

After all that, it must have been a bad connection from a senor. A took it to a mechanic, who just unplugged and plugged things back in. This solved the power problem and also the noticable puffing exhaust - he said it may had been running lean. After that, I changed transmission fluid, which was black as death, and filter. Then for good measure, transfer case fluid. Soon after, I took the intake resonator off, and its been better than ever. I'm making close to 13l/100km (91 octane) straight city now, which is nice.