Going back to the thread linked above...in September 2019, fellow user Yoda's Master suggested that perhaps spacing out the O2 sensor(s) was an option. Unfortunately, it seems the post was lost in the shuffle of the other posts and no one tried. Fast forward to July 2020 and it was mentioned to me to try the same thing in another conversation and I decided to give it a shot. Worst case, I lose like $12. No big deal.
Well, I finally got around to trying it. And what do you know!? It fixed my issue. But, there is a consequence (there is always a 'but' in life, right?). While the fix fixed my P0420 it seems (I've now done nearly 60 miles after clearning my computer and all emissions tests were completed), it did result in the code P2A00 (O2 Sensor Circuit Range/Performance bank1 Sensor 1). This may or may not happen on every vehicle that attempts this P0420/P0430 workaround, but it is important to note. Prior to the implementation of this workaround, the only code I was getting was P0420.
Here is a quick HowTo on what exactly I did.
NOTE: The HowTo had its information updated later in the thread. Make sure to read the whole first two pages.
*Disclaimer* - I am not liable for anything you do to your car. This is just a basic walkthrough.
Task: Fix the P0420/P0430 code using a spark plug anti-fouler to space the O2 sensor(s)
Time: Took me about 35-40 minutes but I took my time
Tools/Supplies Needed:
- 7/8th or 22mm Socket/Wrench
- Wire Brush, Pad or Wheel
- Safety goggles/glasses/shield (safety first)
- 5/16, 3/8, 1/2 and a slightly bigger than 1/2 drill bit
- 18mm Spark Plug Non-Fouler (such as Dorman #42009 which can be had on Amazon for a few bucks)
Note: The above non-fouler will only work for bank 1. Bank 2 results in the transmission oil pan being in the way, but I have been told there is a 90* non-fouler that may work in this situation. Perhaps something like this?
1) Lift the car either using jack stands or a lift. Make sure the car is secure.
2) Here are the two sensors that result in the P0420 or P0430 code. The driver side is bank 1 and gives the P0420. The passenger side is bank 2 and gives the P0430.
3) Driver side sensor:
Passenger side sensor:
4) Remove the sensor you wish to work on. In my case, I was attempting the test of the non-foulers on the bank 2 sensor.
5) Here is a picture of one of the non-foulers from the top:
6) What you now need to do is take one of the non-foulers and drill out the center using the drill bits. Start with the smaller bit and work your way up until you can easily screw the Oxygen sensor into the non-fouler. In my case, I used the size listed above (the last one was ~14mm). Here is a picture of one of the non-foulers after I had completed drilling it out with my drill press:
7) Next, screw the O2 sensor into the non-fouler that you drilled out:
8) Next, add the non-fouler that hasn't been drilled out. It should look like this:
9) Install the now-extended/spaced sensor back into bank 1. Note the note above in the supplies list. This will not work for bank 2 due to the transmission oil pan.
