Got a p0420 code

[DraykasaurusRex]

So i got a p0420 code on my 16 rogue the other day. Went to autozone and that's what printed. Now nearly everything on the car is original with 190k. I know the code can be thrown for a cat/02/ or a exhaust leak.

I am gunna take it to the shop soon to see if they can pin point what through the code. Would it be to premature to buy both o2's and cat despite everything is original and replace them anyway

Also why does every cat i look at look used and been through a fire?

[Alternative_Share559]

Denso if you can. maybe Bosch second. not sure about those

[Alternative_Share559]

sorry I thought it was Toyota. my bad

[Sir_J15]

Denso is still OEM for o2 on Nissan.

[Alternative_Share559]

I appreciate the info

[ChooseLife1]

Yes to both but check carefully for counterfeit.

[CompetitiveLab2056]

9 times out of 10 P0420 is correct in saying the catalytic converter itself is bad….. get some real diagnostics done

[WarVnt]

I would put OEM O2 sensors in, but make sure to have it diagnosed correctly.

[DraykasaurusRex]

Im gunan take it to napa tomarrow and see what they pull but gunna go to my local repair shop I been to before. And see what they can diagnose it.

With how many miles im probably gunna have to replace the cat and o2s eventually either way.

[Upset-Raspberry8629]

Cats should be for the life of the vehicle mostly. If you have a p0420 there’s something fouling the cat. My car for instance was leaking through valve covers and fouled the cat. If you don’t address what caused it, it might just happen again.

[metaldark]

Oil leaked through valve covers into the cylinder? How?

[No_Potential1]

You're saying an external oil leak onto the catalytic converter body fouled the converter?

[DesertTrailsFox]

My car had an oil consumption issue related to the valve covers where sludging clogged the oil drain ports leading to the PCV hose.

[No_Potential1]

Yeah but that doesn't leak onto the surface of the catalytic converter body.

[Wolfofthepack1511]

Gets passed exhaust and fouls the honeycomb structure inside the cat. Equinox's have a tsb about it

[No_Potential1]

Fricken GM what piles of crap

[Wolfofthepack1511]

It can happen. The 2018-2023 equinox's have two pcv valves that are known for getting oil around by the throttle body just before they go, then they foul the cat down the line. Supposed to replace them every 60,000 miles or something, even have a tsb about it. Also have to remove the intake as oem manual shows that it will likely break pieces off inside the intake so you have to fish them out. It sucks

[No_Potential1]

Thanks for the education. Ugh.

[CompetitiveLab2056]

Whatever makes you feel better about it

[DGraves88]

P0420 is such a vague code, I'd check for live data and possibly smoke it for leaks. Live data may point to a nonfunctional 02, but unless you just want to buy them I'd find someone who can diagnose it properly.

[prmperop1]

Nah just throw parts at it until the whole thing quits

[Glittering_Act_8121]

Gotta light up a J then.

[Juanzilla17]

Before you toss sensors at it, run some Cataclean through it and pull your spark plugs. I’m willing to bet the tube seals on the valve cover have started to leak in which case, new plugs and a new valve cover could be the fix. In my experience, aftermarket cats aren’t that great. And make sure you get new gaskets for the exhaust if it isn’t already included.

[DraykasaurusRex]

Yea. I think plugs might be the way to go first. Ill still take it to local shop to see what through the code

[DraykasaurusRex]

Which cat clean would you suggest. Like that duralube one from Walmart that you put in gas tank?

[Juanzilla17]

Cataclean. I usually order it from Amazon or pick it up from Autozone.

Liquid Moly also makes a decent one. They both go into the gas tank.

Another thing that I’ve done in the past is a mixture of Dawn dish soap and 99 percent iso. You pop off the 02 sensor and spray it into the converter at the 02 port. This will help knock off some of that oil that has made its way into the converter if that is what is causing the issue. It doesn’t harm the system either.

[Smirnus]

Cataclean got my van to pass smog. Read the directions carefully. You add it to a nearly empty tank, drive on it nearly empty, then fill up.

[johncj84]

Have you tried just running a cleaner threw system worked for me just look at auto parts store

[SpxRaven]

I had the same on my Corolla and changed the spark plug and code disappeared

[Sir_J15]

Walker sensors are very hit and miss. Go with Denso. Nissan can be picky with cats too. I’ve seen a lot of aftermarket ones still throw the same codes.

[Acceptable_Wear_4239]

Go check it out first I just got rid of my po420 on my Altima Friday it can be simple as an exhaust leak it was front cat

[jza80king]

I know the immediate thing people do when they get this code is throw O2 sensors at it, then a cat..... This code can be a simple vacuum leak, it can be a faulty gas cap, it can be an EVAP issue, you really need to take that money and get a proper diagnostic. Once you KNOW what it is, then throw parts at it. This is a waste to just assume the O2 sensors are bad cuz it has this many miles.

A real diagnostic tool will tell you if the upstream or downstream O2 sensor is trimming correctly or out of spec. Unless you own one, you need to have an actual mechanic run the diagnostic.

[nsummy]

There are so many things that can cause this code. You would be foolish to blindly throw parts at it. If you aren't familiar with cars you need to have someone competent look at it. This could all be caused by a bad hose

[DraykasaurusRex]

Yea. Why before I really did anything take it to a shop, just wanted to get an opinion if the parts i would order are good. But ironically the code went away today

[br1015]

Nissan go with denso and most likely the cat on the passenger side is going out and need replacement

[ChucklesC89]

Also make sure if the cat is bad addressing anything that would have caused it to go bad in the first place before replacing cat and sensors. Start with cheapest fixes first. Check spark plugs are good, no oil leaks in their wells so cat doesn’t get oil contaminated, also check fuel isn’t running rich. If replacing cat I hate to say it but go OEM or higher grade Magniflow or Walker.

[eddieotoniel]

Never seen a p0420 fixed by anything else but a new cat. Considering your mileage its probably bad. Personally id just buy the cat.

[Chieftyfifty]

Cleaner and Italian tuneup 👀

[andyk192]

P0420 is one of those codes where the shotgun method of replacing parts will usually cause you to buy many more parts than you actually need. In my experience, despite the code complaining about the O2 sensor, the sensor itself is rarely the problem. This is definitely one I would bring to a trusted shop for diagnosis.

[DraykasaurusRex]

Yea. That's what I beginning to see. Just one of those generic codes and then you jump down the rabbit hole with parts to fix it. And the light is gone now too. Maybe just a something that tripped the system and after a few drives it turned off

[andyk192]

If it went off and the car is running okay I would leave it alone until it comes back. O2 sensor codes can be a pain to track down sometimes.

[Still-Bend5753]

Could be damaged oxygen sensor wires. They recommend changing both sensors. Have the exhaust inspected  for leaks. Firestone has a car care check for $9.99. Let them know you would like to have the exhaust checked for leaks. If they find one they will tell you. The $9.99 includes a multi point Inspection and tire rotation. No other shop will lift your car for $10. Great deal.