2003 Murano SES 0420 Error Code

[dogbone23]

you can also play around with the one in front since it's easier to get to in order to figure out how the best way would be to get the clips off. they are a pain.

[jonUF02]

Originally Posted by Warhammer

LOL...when I saw this post I immediately thought "4:20PM". It may simply be if your MO throws a 0420 code it wants some weed!

Well, I thought the same thing, but I tired blowing some very kind bud in the air intake and it did not stop the code .

It started with code p1273, but only on long trips. I have been shutting it off, but now it randomly puts out code P0420 instead. I just replaced the spark plugs and bank 1 sensor 1 O2 sensor last weekend. I went on a trip this weekend and the code P0420 came back. I guess I will have to replace the bank one precat. I think it's going to be expensive.

I already save $550 off the dealer quote for the spark plugs and sensor thanks to posts on this forum I was able to tackle it in a few hours. FYI: the Bosch sensor sold at Discount Auto Parts for $110 is identical to the Nissan O2 sensor, with clips and everything. If you look at the old sensor it is stamped with Nissan logo, then it says Germany... obviously Bosch. The dealer wanted $180 for the same part.

I noticed that my rear bank cylinders were noticeably darker on the intake manifold when I had it apart. Does anyone know what this means?

[jeronimo6972]

Hi all,

I am new to the forum and just trying to educate myself so I don't feel like I am getting it right up #$%@ from the dealer. This thread as been pretty helpful already but is alos a little above me. I have an 03 MO SL, 118k mi - few months ago the check engine light came on and now at least I am smart enough to get the code and research a little. The ck engine light has been going on and off. Well, I ended up going to the dealer for other issues and had them confirm the P0420 - They said I need a new cat converter and said it would cost around $1300-$1400. Instead, I had all the other service they said I also needed which was - new spark plugs, O ring (oil was leaking) CVT service, rear breaks - total cost $1600...

I held off on the cat converter cuz can't afford it all right now. I asked if it's bad to keep driving it with this - he said it would eventually damage the engine - is this true?? After reading this thread, seems like possibly the new spark plugs can take care of it? Also thinking if I need it replaced I can have it done for way cheaper somewhere else...

thanks for any advice - this forum has already been helpful!

new guy

[turbizzy]

Its tough to really predict what will happen if you keep driving around with a faulty cat. In most cases, a bad cat will be ok to drive around with for a while but eventually the cat will begin to degrade and start falling apart which could lead to the catalyst material clogging the downstream cat converter in the Y pipe and essentially choking the exhaust and causing severe power loss. Or even worse, the catalyst material could get sucked back into the cylinders during "REVERSION" in which case the catalyst turns into really fine sand-type material and will severely damage your cylinders and rings which could lead to compression loss and/or oil consumption.

These are worse case scenarios of course, but with the stuff i've seen happen with these cats and engines, this could happen.

[Compton]

Hi,

I am also getting the P0420 error (bank 1). Can someone tell me which part #'s for the O2 sensor and the cat that I would need for a 2005 FWD Murano?

I am going to replace the spark plugs and O2 sensor first and see if that fixes the issue.

thanks

[jonUF02]

Originally Posted by Compton

Hi,

I am also getting the P0420 error (bank 1). Can someone tell me which part #'s for the O2 sensor and the cat that I would need for a 2005 FWD Murano?

I am going to replace the spark plugs and O2 sensor first and see if that fixes the issue.

thanks

This is exactly as I just did. Do not buy the Nissan o2 sensor, as it is the same as the Bosch part I got from Advance Auto for about $70 less than dealer list. It is this part:

Buy Bosch Premium Oxygen Sensor 15525 at Advance Auto Parts_____

It has all the exact clips as the original, and the original was stamped as "Germany" so it is obviously Bosch.

After I did all the work to replace the plugs and sensor, I am still getting lower voltage readings from this sensor, and the code P0420 came back, so it was not the sensor that was bad. I will probably replace the rear pre-cat soon. It is not hard to reach the bolts from under the car. RockAuto.com has a direct-fit precat as low as $215, but I think I'm going to spend a bit more on the stainless one from MagnaFlow here:

Buy MagnaFlow Direct Fit Catalytic Converter, Stainless Steel 50219 at Advance Auto Parts_____

If you look arond the web for coupon codes you can probably save about 15-20% and pick up the items at the local store.

I don't really feel comfortable working under the car at home (just a mental thing), so I will probably take it to a muffler shop to do the CAT. I would question anything over 1 hour of labor on that after having a look at it. They will probably use the same part I linked above, so I know what they are paying.

[Compton]

Thanks for the reply.. Are you sure about the 15525 part # for the o2 and the 50219 number for the cat? Those part #'s are for the downstream o2 sensor and cat according to Rockauto.com

Someone else on another thread said the Bank 1 is the upstream sensor..
I don't know the answer... just trying to clarify.

Thanks

Thanks

Originally Posted by jonUF02

This is exactly as I just did. Do not buy the Nissan o2 sensor, as it is the same as the Bosch part I got from Advance Auto for about $70 less than dealer list. It is this part:

Buy Bosch Premium Oxygen Sensor 15525 at Advance Auto Parts_____

It has all the exact clips as the original, and the original was stamped as "Germany" so it is obviously Bosch.

After I did all the work to replace the plugs and sensor, I am still getting lower voltage readings from this sensor, and the code P0420 came back, so it was not the sensor that was bad. I will probably replace the rear pre-cat soon. It is not hard to reach the bolts from under the car. RockAuto.com has a direct-fit precat as low as $215, but I think I'm going to spend a bit more on the stainless one from MagnaFlow here:

Buy MagnaFlow Direct Fit Catalytic Converter, Stainless Steel 50219 at Advance Auto Parts_____

If you look arond the web for coupon codes you can probably save about 15-20% and pick up the items at the local store.

I don't really feel comfortable working under the car at home (just a mental thing), so I will probably take it to a muffler shop to do the CAT. I would question anything over 1 hour of labor on that after having a look at it. They will probably use the same part I linked above, so I know what they are paying.

[jonUF02]

I know the CAT is correct based on the picture. I looked at the flanges and bolt positions, and there is no way I could mix up the 3 different converters, they are all totally different. I am not 100% on the sensor, but I know that I took my old one to Advance and matched it up perfectly and paid $110 for it. I kept the old one in the new box so I will double-check when I get a chance. Direct replacement, same readings, so I guess I wasted $110 on a hope that it was the sensor and not the more expensive thing being sensed correctly.

I have a cheap Ebay OBDII reader that hooks to my laptop, using Digimoto Lite free software to get the voltage readings from the sensors. The Bank 1, Sensor 1 is getting a way lower reading than the Bank 2 Sensor 1, as it was before I replaced the sensor as well. I don't fully understand this since the sensor in question is BEFORE the pre-cat that is defective??? Can anyone explain?

I will say that the spark plugs seem to have smoothed out the idle. I was getting some noticable oil consumption between changes, and I was worried that my precat may have already toasted my engine, but now it seems better after the new plugs. 1000 miles and the oil looks good. I think I have a little drip around the oil pump hose or maybe one of the axle seals, but not enough that it leaves any drips on the driveway, just a little oily when I look up unerneath.

I have sunk thousands into recent maintenance repairs of this vehicle despite being a very mechanically savvy guy and fixing lots of stuff myself. I only have only about 110K on it. I am thinking of trading it for the VW Touareg that my wife wants. I'm really doubting the Nissan V6 and overall engineering at this point because my 2001 Pathfinder with the same engine blew a head gasket at 125K. My Altima with the 2.5 has been flawless, only brakes and tires and one $50 sensor, just passed 100K. I see a lot of very well documented common problems among Nissans like the precat situation that they simply will not own up to and recall or help us out with cheap parts.

[nitely]

Regarding O2 sensors...I would get the oem just to be sure. I recently replaced a friends toyota corolla 2001 O2 sensor and it will not take anything but the oem...aftermarket ones just gives all sort of issues including the check engine light that will never go away. I know it cost more but no hassles once installed.

[jonUF02]

Originally Posted by nitely

Regarding O2 sensors...I would get the oem just to be sure. I recently replaced a friends toyota corolla 2001 O2 sensor and it will not take anything but the oem...aftermarket ones just gives all sort of issues including the check engine light that will never go away. I know it cost more but no hassles once installed.

I only purchased the Bosch branded part after taking out the original and seeing that it was stamped as "Germany" right on it, then I took it and saw it was an absolutely IDENTICAL match to the Bosch sensor sold at Advance, all the connections and even the clips that hold the wire in place were exactly the same. I would generally agree with your statement, and almost bought the Nissan part until I removed it, made these observations, and saved $70 on the exact same part less the little Nissan logo added to it. I would NOT buy the "generic" sensors where you have to splice wires and stuff.

There are only so many parts suppliers in the world. I also own a Mercedes CLK and there are many dealer parts that are made by Bosch who sells identical replacements without the huge dealer markup. You can probably buy "Nissan" branded spark plugs as well, but they are just NGK in an expensive box.

[jonUF02]

I completed the install of my bank 1 (firewall side) precat. I used the Walker brand "direct fit" replacement. I will now recind my previous statement regarding labor, this was a B!TC# of a job and took days, mostly because I wanted to be sure I could remove the old part before ordering the new one (no local stock anywhere). Good thing I have an extra car right now. It seems to be good according to the variation in voltage readings from the OBD2 and sounds/feels fine. It is strange that each of the sensors has a different voltage range, but according to my info, the variation is what affects the P0420 code regarding "efficiency below threshold". The original precat was not discentegrated or turned to dust inside, so that is peace of mind for the engine.

The reason that the labor was a pain was that there are 4 bolts holding the top end; 2 can be easily accessed from below and took some gorilla grip on a breaker bar to get loose. Fortunately I don't have to worry about further hassles with rusted parts/bolts since I am in Florida, but that could definitely complicate things up north. I believe thes original bolts and nuts are aluminum on this side becuse they did not stick to my magnet tray. At least they thought ahead on one thing! The other 2 are studs that thread into the original part and have nuts on the top side of the exhaust manifold next to the O2 sensor. To get to this area you have to dismantle the top side of the engine bay and remove the intake manifold/TB assembly according to the insturctions posted that I followed when replacing the spark plugs and sensor on my first attempt.

According to Walker, the part is a direct OEM fit, but it is not. It does not have threads for the original studs to go back in, but only larger holes where they would go. I am assuming any other aftermarket part will not have the stud threads either. It also did not have all the welded on heat shields that the original part had. I was able to buy some nuts/bolts in place of the studs, but getting them in was the biggest pain of all. I was working blind on the back side of the engine while basically sitting on top of the engine, trying to hold a bolt and thread a nut with one hand, totally by feel, while the heat shield was cutting up my hands and arms because it can not be removed, just pushed out of the way as much as possible. I guess the hassle was worth it since the Nissan part is around $600 vs. $275 for the Walker. I also installed a new metal crush gasket on the top of the precat per the service manual.

Once I got past the hassles of the rear bolts/studs situatuion, everything went back together fine. It is just a lot more labor than anticipated.

Here is what you need:

• Ramps to access the under side and stool to access the top
• breaker bar, PB blast, and a gorilla grip to remove the exhaust bolts.
• Precat replacement part (~$275 @ RockAuto)
• metal crush washer that goes between the manifold and precat (~$13 @ Advance Auto)
• 2 good bolts, about 1.5" long with nuts and tooth grip washers. They need to be long enough to go all the way through both pieces of metal and get the nuts on. Get the size that fits the original stud nuts. The tooth washers allow the bolt to grip and be tightened from one side since you can't really get a wrench on the bottom side.
• Directions to remove the intake maniford and TB found on this forum
• new intake manifold gasket for reassembly (~$35 @ Advance Auto)

• Good tools
• A solid weekend or an extra car to drive
• A case of good beer and a radio
• A boat load of patience
• Some band-aids for your busted knuckles

After all of this, I think I spent less than $400 vs. probably around $1200 or more at the dealer. Let's hope the light stays out, but I am more relieved to know that I am not sucking dust into the engine and destroying it. You could also do the spark plugs and other jobs while you have the engine bay apart. I think my PS hose is leaking (common), and maybe a tiny drip from the rear valve cover, but I will fight that another day since no stains on the driveway yet.

[folgersoldier]

John,

Just for clarification. After you changed the precat the voltage readings were better on the O2 sensor for that bank? I have most of the parts but still have no time to tackle it yet. Also I bought my precat from rock but it was around 215 and came with the crush washers, I don't remember which one I got though.

[folgersoldier]

Also did you weld the heat shields onto the replacement or did you leave them off?

[gofastinc]

Ok everyone,Ii have the dreaded P0420 code as well. I reset it a few weeks ago and it returned. From what I have read and understand, I should probably replace the cat. I put an aftermarket cat on a sentra a few years ago and it didn't last very long so I have the amae concerns for this situation. I would like to hear from those of you that have tried aftermarket cats and if you would use them again, or if it was a waste of time and money. Thanks.