Need help with P0420 DIY?

[Sundevil84]

Hi my Murnano is getting SES light and the code is P0420 bank 1. I know that this means my catalytic converter near the firewall is failing. I have searched and I found the part but I have not found any DIY for this fix. Does anyone know of any guides online or does anyone have any advice for trying to replace the cat? I imagine it can't be that fun of a job but any help would be greatly appreciated.

Thanks

[darkredmurano]

here you go, read what it has to say, then read the comments below
OBDII Code P0420 NISSAN - Catalyst System Efficiency Below Threshold Bank 1 | Engine-Codes.com

seems like its a pretty common problem and, although im a little skeptical on this fix, it doesn't cost much to try it out.

best way to do it i would suggest would be drive til you have almost an emtpy tank then put some of that fuel treatment/injector cleaner stuff (the guy mentions STP and his worked) and then fill up with premium(has better detergents than regular unleaded) and i would pull the negative cable off your battery and let it sit for 15 mins so it resets the ECU then reconnect and give it a solid 100 miles before re-assessing the situation.

o and a FYI, just because the code that you pulled says a part name, DOES NOT mean that THAT part is failing, sensors that report to the computer that say that part is passing/failing could also be at fault, O2 sensors (oxygen sensors) go bad ALL THE TIME, just some food for thought before you go replacing that costly catalytic converter.

be sure to report back whether it works or not so others can see the fix/we can get this figured out

[nitely]

I agree. Don't be too hasty in changing out your cat converter. What year and mileage is your MO? Are you experiencing a lot of oil consumption? Maybe coolant smell in the garage or when driving? Hesitations? Poor idling?

[Mr3Putt]

I had this issue for many miles. My mechanic said my cats were fine. The O2 sensor was a tad too sensitive and was throwing the code every few hundred miles.

I fixed it myself for less than $5.

I bought a spark plug non fouler

Widened the fouler out with a 1/2 inch drill bit.

Screwed the O2 sensor into the non fouler.

Screwed the whole stack back onto the exhaust pipe.

TIP: Unhook the electrical end of the O2 sensor so you can freely screw the things together

I reset the ses light and drove almost 10,000 miles and never saw the code again. The car subsequently passed PA emissions with flying colors.

It works because it holds the O2 sensor slightly out of the line of fire. If your Cat really blows, it should foul the O2 enough that the sensor will pick it up.

DISCLAIMER: This worked for me. If you do this and die, it's not my fault.

[Compton]

Does anyone have the correct part #'s for both the o2 and the cat for this code? THanks

[njjoe]

Ingenious!

-njjoe

Originally Posted by Mr3Putt

I had this issue for many miles. My mechanic said my cats were fine. The O2 sensor was a tad too sensitive and was throwing the code every few hundred miles.

I fixed it myself for less than $5.

I bought a spark plug non fouler

Widened the fouler out with a 1/2 inch drill bit.

Screwed the O2 sensor into the non fouler.

Screwed the whole stack back onto the exhaust pipe.

TIP: Unhook the electrical end of the O2 sensor so you can freely screw the things together

I reset the ses light and drove almost 10,000 miles and never saw the code again. The car subsequently passed PA emissions with flying colors.

It works because it holds the O2 sensor slightly out of the line of fire. If your Cat really blows, it should foul the O2 enough that the sensor will pick it up.

DISCLAIMER: This worked for me. If you do this and die, it's not my fault.

[darkredmurano]

Originally Posted by Compton

Does anyone have the correct part #'s for both the o2 and the cat for this code? THanks

year and package/options of your MO


or you can search any of the sites that are easily found via google, www.rockauto.com comes to mind since ive used them before and they have OEM parts.

[Compton]

Mine is a 2005 SL FWD. I look at rockauto but it had multiple o2 sensors and I wasnt sure which 1 was Bank 1.

[darkredmurano]

Originally Posted by Compton

Mine is a 2005 SL FWD. I look at rockauto but it had multiple o2 sensors and I wasnt sure which 1 was Bank 1.

Bank 1 sensor 1 should be the sensor on the forward manifold down pipe, which is the left side of the engine in correlation to the flywheel, which should be the driver's side but since this is a fwd vehicle you cant just say driver's side it's the front.


and it looks like from a lil research that both (Bank 1 and Bank 2) of the upstream sensors are the exact same, just look for "Before Cat/Pre-Cat" or "Upstream" they are all the same meaning.

and if you're like me and don't like waiting for shipping you can go to autozone, they sell the Denso Sensors, i wouldn't do the Bosch's...too many stories of them failing prematurely, Denso is what Nissan uses from the factory, so that's what i would stick with if i were you.


and just a lil info..because i like to be all inclusive, "Technically" the two upstream sensors are not Oxygen sensors, they are wide band Air/Fuel ratio (AFR) sensors, the sensor located downstream is a regular Oxygen sensor or O2 sensor

[KtG]

The cats carry an 8year/80k mile warranty, if you fit that, let the dealer install a new cat.

P0420 is very common, the B1 cat is not well ventilated, and Nissan cant built a cat to save their lives anyway. They are problematic on almost every model. Because of this, I cannot advocate tricking the system with the spacers (this is also technically illegal) as the cat will eventually degrade to the point where it breaks up and chunks get sucked into the engine. Previous-gen QR25 alts were notorious for this, and Ive seen it on several VQs as well.

[Bry06MO]

Originally Posted by KtG

as the cat will eventually degrade to the point where it breaks up and chunks get sucked into the engine

How so when exhaust flows out of the vehicle and not in?

Originally Posted by Sundevil84

Hi my Murnano is getting SES light and the code is P0420 bank 1. I know that this means my catalytic converter near the firewall is failing. I have searched and I found the part but I have not found any DIY for this fix. Does anyone know of any guides online or does anyone have any advice for trying to replace the cat? I imagine it can't be that fun of a job but any help would be greatly appreciated.

Thanks

What did you find out? I just got the code and I'm planning on changing the O2 sensor and going from there.

[njjoe]

Originally Posted by Bry06MO

How so when exhaust flows out of the vehicle and not in?

As unlikely as it seems, the pieces can ride the exhaust pulse pressure waves back into the combustion chamber. Once there they will wreak havoc on the rings and cylinder walls.

-njjoe

[nitely]

Originally Posted by Bry06MO

What did you find out? I just got the code and I'm planning on changing the O2 sensor and going from there.

What year and mileage is your MO? I would take darkredmuranos advice first and fill up with premium fuel and dose it with chevron techron concentrate fuel system cleaner. Then erase the code and see if it comes back. I had the P0420 code on my 99 odyssey with 170k original CAT and o2 sensors last February. Did the above procedure and so far the code has not returned. How much is your oil consumption? And if you're really eager to change the o2 sensors, I'd recommend using oem to avoid any issues. Good luck.

[Bry06MO]

Originally Posted by nitely

What year and mileage is your MO? I would take darkredmuranos advice first and fill up with premium fuel and dose it with chevron techron concentrate fuel system cleaner. Then erase the code and see if it comes back. I had the P0420 code on my 99 odyssey with 170k original CAT and o2 sensors last February. Did the above procedure and so far the code has not returned. How much is your oil consumption? And if you're really eager to change the o2 sensors, I'd recommend using oem to avoid any issues. Good luck.

06 with 101K (yes, I drive a lot). I'll give the fuel treatment fix a try and see what happens fist. It needs gas anyway, so I can do it today.

[nitely]

You are about due for the spark plugs. That could help too if the first fix does not work. For a six year old CAT its too early to fail unless you are burning lots of oil and running rich or even have a coolant leak in the engine.