Acid bath and P0420

Was getting the cat below threshold code after each startup. I must have reset it 40+ times over the last 6 months.

I decided to try the Oxalic and Citric acid bath this weekend (0.1M of oxalic acid + 0.1M of citric acid). Let the cat soak for 6 hours with occasional agitation. I was going to use a pump but the darn thing was broken so I just agitated the bucket every 30 minutes or so.

Re-assembled and started car. Within 5 minutes of driving, all the emissions startup cycles went green:



Previously it would take 20 minutes before catalyst would complete and then I'd get an engine check light. So I took this as a very good sign.

However, this morning, after the car sat all night, I started it and the emissions showed ready immediately right at startup. So then I let it sit again today for 5 hours and start it up and still everything comes up ready immediately again. Is this normal?

 

The cat is at the very front of the pipe so you only need about 14" of water.

 

4 service ramps to elevate the car, an O2 sensor wrench(I'd just replaced the O2 sensor a few weeks ago with no luck), a 14mm socket and extension of at least 12" and preferably a 1/2" driver and a breaker bar.

Removing the entire assembly is about a 5 minute job assuming you don't have to deal with a frozen O2 sensor. My old o2 sensor from a few weeks ago was seized and I had to let the threads soak in PB blaster for a few hours before it broke free. Didn't want to risk breaking off the O2 bung by over torquing with the breaker bar.

 

Well that makes sense since the error hasn't returned. Note, resetting the fault doesn't clear the status then, just the the codes.

 

Just drove another 140 miles. Still no P0420.

 

Not celebrating until I smog the car next month when I get my renewal notice.

I basically followed this video:

and produced 8 gallons of solution for the size of container I had.

The fluid was a dark green. The cat was not clogged prior but it was coated with ash that did not come off flushing with water.

I burn about a qt of oil every 5K miles.

 

I think the amount of oil being burned is small enough that it would take a 100K miles to ruin a new cat. Reg is due on 9/22. I should get the renewal notice next month. Smog is good for 90 days but I'm not sure if that's only for selling. I thought about doing it exactly 90 days before the due date which would be around the 25th of this month.

 

CA but 223K miles.