Mechanical O2 Sensor Bypass Didn't Work?

[DSN46]

Howdy,

 

I am getting the dreaded P0420 code from Bank 1. Both Sensors are relatively new on both sides. The idiot previous owner put some cheap aftermarket high-flow CATs on. I know this is why the code keeps popping.

 

So.. I had been reading about the spark plug anti-fouler trick to move the sensor away from the exhaust stream and "trick" the PCM that all is well.

 

I did this tonight and used my scanner to reset the SES light.

Well... not even 1 hour of driving and the code popped again.

 

Anyone try this trick and have it actually WORK?

I really dont want to put out the bucks for a OEM CAT!

 

Thank you for any replies or advice. (or ANY aftermarket CAT that actually works)

 

James

[97SierraGMC]

Mangaflow makes some pretty nice cats that dont cost very much....

[svensk]

Have a tuner shut off the damn sensors.

[Zembonez]

Swap the lead sensor from side to side and see if the problem goes away or moves. I had a similar problem on a Suburban and moving the new sensor to the other side fixed it. I guess the tolerance for the new sensor somehow was just out of spec? Anyway, the SES code never came back. Easy to try.

[Zembonez]

Sorry... double posted. I guess this new faster site has me all confused.

[DSN46]

Thank you all for the replies!

 

I will try swapping lead sensors side to side before doing anything else.

If that fails, then it looks like a Magnaflow is in my future.

 

I would love to have the post-cat sensors tuned out, but I dont have a Diablo tuner, and there is no way I can have the truck down while I send off the PCM to someone to flash it.

 

Thanks again.

 

James

[xwire]

Thank you all for the replies!

 

I will try swapping lead sensors side to side before doing anything else.

If that fails, then it looks like a Magnaflow is in my future.

 

I would love to have the post-cat sensors tuned out, but I dont have a Diablo tuner, and there is no way I can have the truck down while I send off the PCM to someone to flash it.

 

Thanks again.

 

James

 

 

O2 sims work wonders in situations like these, and are easily hidden so everything looks good come inspection time

[DSN46]

I have read about the O2 sims. And that is still a possibility! I just didnt want to buy one until I had gone through everything free that I could.

 

I went out and swapped the lead sensors from side to side.... We'll see what happens when I drive it today. I just have this gut-feeling that I'm gonna see that damn light again...

 

Thank you very much for all the kind advice.

 

James

[DSN46]

YEP!

Light came on and it threw the code.... Darn!

 

Looks like it's either:

1. Live with the light and put a piece of black tape over it.

2. Try an electronic O2 simulator.

3. Go get a Mangaflow CAT put on.

 

Not too happy bout this one that's for sure.

 

James

[DSN46]

For those of you subscribed to this thread, and for future searches on this subject:

 

Today, I cleaned the &*^% out of my Throttle Body. Got all kinds of thick black "muck" out of it and off the butterfly plate. Drove about 20 miles and the light WENT OUT! All by itself...

Either it is one heck of a coincidence, OR the anti-fouler stacking took several "run-start-run" cycles to fool the PCM. Anyone have a guess?

 

Anyway, I"m sure happy. And she purrs like a kitten now with the throttle body all shiny again!

 

Thank you all,

 

James