Code p0420 options

[Greencamaro1234]

Originally Posted by '10CamaroDude

UPDATE:

You must use FACTORY O2 Downstream sensors, and add spacers to get rid of
the P0420 and P0430. I was plagued with this, as where the car lot I bought it from
had the car for ten weeks and could not fix it. They said they used AC Delco sensors
and they lied. They also drilled holes in the tip of the LH downstream sensor.

8 hours, over 4 weeks, I was able to clear it as soon as I replaced the crap BOSCH
sensor with a FACTORY sensor on the driver side.

Driver side:

This is equivalent to three anti-foul spacers. I used a REAL stainless spacer, then
put an anti-foul spacer in front of it. Cleared the P0430. With the Bosch sensor, I
went three deep, and it still didn't work. It has to be factory sensors.


Passenger side:

Only needed two spacers for the passenger side, cleared P0420.

I passed PA Emissions, and the secondary cats are gone. I also found one of them was
gutted, so I had to remove them both to even the exhaust flow. I will put factory
ones back on if I can find them.

I’m having this problem now 147k so curious if this did solve the problem,and curious why all the adapters,couldn’t you just replace with the new sensors without these adapters.

[TaeKwonJOE]

Originally Posted by justa25thTA

https://www.walmart.com/ip/Dorman-42...&wl13=&veh=sem

I've had this code off and on since I got the new engine. So Doorman 42009 (18mm) for an LLT, correct? I saw another post that said 14mm I think, which wouldn't be 42009.

[G8One2]

Exhaust leaks, even very small ones upstream from the O2's can also cause this.

[NOT A 45]

I see tons of misinformation on this thread. Quickly, without conducting a seminar this is how it works. On a V8 you have 4 heated O2 sensors. The pre cat sensors are strictly for fuel delivery. The post cat sensors are catalyst monitoring sensors....that is their only job. They work by creating a voltage and the range is around 100mv-800mv. Key on engine off the normal voltage is 450mv. Engine running the primary O2's will fluctuate between 100-800mv but generally average 450mv between the high and low. Once the converter is at operating temperature and doing what it's supposed to the post O2's will read very close to 450mv and fluctuate very little. Now when the catalyst isn't functioning the post O2's will mirror what the primary O2 reads. This is how the ECM knows the cat is either missing or degraded. The reason the anti fouler may work is because it pulls the sensing element of the O2 out of the exhaust stream. Other than turning on the light, running the car with a bad cat will not cause any problem to the car as long as it's not restricted.

[1JEWLDSSRS]

Originally Posted by NOT A 45

I see tons of misinformation on this thread. Quickly, without conducting a seminar this is how it works. On a V8 you have 4 heated O2 sensors. The pre cat sensors are strictly for fuel delivery. The post cat sensors are catalyst monitoring sensors....that is their only job. They work by creating a voltage and the range is around 100mv-800mv. Key on engine off the normal voltage is 450mv. Engine running the primary O2's will fluctuate between 100-800mv but generally average 450mv between the high and low. Once the converter is at operating temperature and doing what it's supposed to the post O2's will read very close to 450mv and fluctuate very little. Now when the catalyst isn't functioning the post O2's will mirror what the primary O2 reads. This is how the ECM knows the cat is either missing or degraded. The reason the anti fouler may work is because it pulls the sensing element of the O2 out of the exhaust stream. Other than turning on the light, running the car with a bad cat will not cause any problem to the car as long as it's not restricted.

Again, awesome info to know, as always. Thanks for ALL your info.. Much appreciated sir!!

[NOT A 45]

Originally Posted by 1JEWLDSSRS

Again, awesome info to know, as always. Thanks for ALL your info.. Much appreciated sir!!

So, taking this to the next level, you might ask yourself.....Why do the primary O2's fluctuate? Rich lean rich lean back and forth. It would seem so simple just to keep the air/fuel ratio constant like a carburetor does. 14.7 to 1 is ideal for combustion. Converters need oxygen to do their job, at 14.7 there isn't enough oxygen for them to accomplish that. So remember back to 70's and 80's cars with air pumps. They injected fresh air directly to the converter. Solenoids and the computer would decide when and how long they would deliver air. Engineers learned that if they just toggle the fuel mixture from rich to lean and average 14.7 to one they could eliminate the need for the air pump and still provide the catalyst with the required oxygen. We still see some air pumps on some cars but they are only there to help the converter "light off" on cold start up. So this fuel strategy of toggling of fuel also enabled for catalyst monitoring. Rich lean rich lean going in, steady coming out...that's how we know our converter is working.

[1JEWLDSSRS]

Originally Posted by NOT A 45

So, taking this to the next level, you might ask yourself.....Why do the primary O2's fluctuate? Rich lean rich lean back and forth. It would seem so simple just to keep the air/fuel ratio constant like a carburetor does. 14.7 to 1 is ideal for combustion. Converters need oxygen to do their job, at 14.7 there isn't enough oxygen for them to accomplish that. So remember back to 70's and 80's cars with air pumps. They injected fresh air directly to the converter. Solenoids and the computer would decide when and how long they would deliver air. Engineers learned that if they just toggle the fuel mixture from rich to lean and average 14.7 to one they could eliminate the need for the air pump and still provide the catalyst with the required oxygen. We still see some air pumps on some cars but they are only there to help the converter "light off" on cold start up. So this fuel strategy of toggling of fuel also enabled for catalyst monitoring. Rich lean rich lean going in, steady coming out...that's how we know our converter is working.