P0420 code

Hey guys, so this morning my CEL and Trac off lights came on. Read the code and it was p0420. I did not notice and performance issues or difference in drivability. I checked all around and could not detect any exhaust leaks. I decided to check the air filter, it looked perfectly clean, cleaned the MAF while I was in there. Anything else easy I should be looking for?

 

Sorry to hear about your P0420 code....let see if we can help.

Top Causes of P0420 in the Toyota Tacoma


There are many things that can cause the P0420 trouble code in your Tacoma. Here are the most common ones.

• Oxygen Sensor– The P0420 codes is thrown when the oxygen sensors on both sides of the exhaust have very similar readings. When the oxygen sensor is bad, it can cause a false reading and trigger the code. If the engine does not exhibit any of the decreased performance associated with a bad catalytic converter, it very well may be the oxygen sensor (if you haven’t noticed the performance loss yet).
• Catalytic Converter– A catalytic converter is responsible for scrubbing out as much pollution as possible from the Tacoma’s exhaust. Over time, they can become clogged. Although, modern catalytic converters are supposed to last the life of most vehicles, it could be there is some underlying problem if it has clogged.
• O2 Sensor Wiring– Over time, the oxygen sensor wiring can go bad. It is especially volatile since it is right next to the hot exhaust at all times. The downstream oxygen sensor wiring is especially volatile since it is so far from the ECM (more distance to travel.
• Tacoma Timing– If your Tacoma is misfiring or the exhaust timing is off, this can affect the gasses that are actually going to the O2 sensors enough to cause the P0420 code to register.
• Exhaust Leak– If there’s a noticeable exhaust leak coming from the vehicle it can change what the O2 sensors register enough to throw the P0420 code.
• Engine Temp Sensor– If the computer doesn’t know what the engine temp is it’ll keep the fuel mixture rich. When the fuel mixture is rich, the exhaust the O2 sensors see will be out of range and it could throw the sensor.

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  On my first Tacoma (1st gen 1996) it had the same code and after removal and replacement of a O2 sensors and catalytic converter we had also a exhaust leak....the story really is about one step at a time. Good that you checked for exhaust leaks first....

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  Good luck...keep us posted!

 

The front catalytic converter on the passenger side is likely the culprit. You might try running some premium gas in it and give her the ol italian tune up. I had this same code on my 4 banger a while back and thats what i did and it hasnt come back in a couple thousand miles. May not work, but that is likely the issue. How many miles on your truck?

URD o2 sims would be an easier fix than swapping manifolds since the front cats are part of the headers

 

Mileage of vehicle?

 

Sorry guys, 90k on the truck. 2015 TRD Sport 4.0L.

Is there anyway to test the O2 sensors? or just replace and hope?

 

I have the same code on 2000 4Runner and it won’t pass the smog here in California. I literally about to give in the truck it has 290k miles I’ve swapped the o2 sensors and nothing. I am thinking it’s going to definitely be the catalytic converter though

 

I had this code on my 06. Turned out to be the gasket connecting the passenger side cats to the Y pipe. Check the connections. I found some soot where it was leaking.

 

i had this error this past month.. was a bad o2 sensor. 06 with 160k.. The other side went off the other week and that was too suspicious for me.. so I got some high octane gas and some emissions cleaner from Advance.. Have not seen the error since.

 

Since its a 2015, URD o2 sims wont play nice with it.. HPtuners would be able to take care of that if you dont want to replace cats but want no cel/trac lights

 

Lifespan of a o2 senors are generally 80,000 but usually last longer.
Did your dtc point to bank 1 or bank 2? If so either swap o2s if broke $$$ or just replace o2 on that side. Or better yet clear code put some quality fuel in it and run the piss out of it a see if dtc returns.

 

I'm about to drive 400 miles so I'm gonna out premium in it and see what happens... My code reader is the most basic one out there, it didn't give me any bank info

 

LOL....drive it like you stole it !!

 

Hit a local auto parts store and have the code read so you know which side. When I had this code I replaced my oxygen sensor on the side the code stated and all has been fine. I got this one on Amazon that was recommended in another thread Walker Products 250-54006 4-Wire Air/Fuel Ratio Sensor

$119 Walker Products 250-54006 4-Wire Air/Fuel Ratio Sensor

https://www.amazon.com/dp/B000C8ZJME/ref=cm_sw_r_cp_api_i_w-mgEbFD8ZNDR.

 

Oh damn! I got that 4x. They seem to respond well in the torque app. When I had the Rasta code bank one O2 sensor was all over the place while bank 2 was smooth.

 

If it's the cat, then it should be covered under warranty. Check your owners manual.

 

Nice having an Ultraguage now to see stuff like this in real time.

 

Iirc that’s for the 4cyl, op has the 6cyl.

 

I thought there was a federal law that covers emission crap for a certain number of years? I remember reading it in the owners manual.

 

Yeah I think all smog related components warranty is 80,000 might be 100,000 I forget.

 

Just to update, drove close to 1,000 miles this week. First 2 tanks were with premium gas. Light hasn't come back on. I would assume if there was an actual problem it would've already come back on.