Catalytic Converter P0430 Repair

[jghall00]

Sharing my post from another forum in case someone else may benefit.
My 2017 Expedition Ecoboost had the P0430 code for over a year. I found instructions from this post.

Procedurally, I soaked the driver's side catalytic converter in a 17-gallon plastic storage tote with citric and oxalic acid. The instructions called for temps of 160 to 175, but I was unable to get the temp over 130 for an extended period using my 120V immersion heater, so I asked one of the LLMs how long to extend the soak time. ChatGPT suggested 12 to 18 hours (up from 6) due to the reduced reaction temp. We had family visiting and I couldn't really mess with it, so I left it to soak for about 19 hours. I hosed down the interior ~4 times at intermittent intervals. The original instructions called for a rinse every hour. The substrate didn't look that bad when I started. It wasn't blackened like some of the ones I've seen in videos, but you can only view the cat matrix through the upstream O2 sensor hole. The acid bath turned green, which I think is a common result when acid and metals react.

Here's the quantity I used per gallon of water.

• 71 grams citric acid
• 24 grams of oxalic acid

Here is a Youtube video that illustrates the process.


To anyone reading this down the road, good luck!

Attachments​

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[The_Jeff]

IIRC, Skotty Kilmer recommends something like this.

Mechanism of action is that the "stuff" is still there, simply covered with "something" that needs to go away.

 

[D60]

The same place that buys cats is buying old 02 sensors -- so if you have a shop start a bucket of old sensors!!

 

[oil pan 4]

Sharing my post from another forum in case someone else may benefit.
My 2017 Expedition Ecoboost had the P0430 code for over a year. I found instructions from this post.

Procedurally, I soaked the driver's side catalytic converter in a 17-gallon plastic storage tote with citric and oxalic acid. The instructions called for temps of 160 to 175, but I was unable to get the temp over 130 for an extended period using my 120V immersion heater, so I asked one of the LLMs how long to extend the soak time. ChatGPT suggested 12 to 18 hours (up from 6) due to the reduced reaction temp. We had family visiting and I couldn't really mess with it, so I left it to soak for about 19 hours. I hosed down the interior ~4 times at intermittent intervals. The original instructions called for a rinse every hour. The substrate didn't look that bad when I started. It wasn't blackened like some of the ones I've seen in videos, but you can only view the cat matrix through the upstream O2 sensor hole. The acid bath turned green, which I think is a common result when acid and metals react.

Here's the quantity I used per gallon of water.

• 71 grams citric acid
• 24 grams of oxalic acid

Here is a Youtube video that illustrates the process.


To anyone reading this down the road, good luck!

Attachments​

• 
  Screenshot_20251223_070047_Torque.png
  111.5 KBViews: 3

I did something like this before. Instead of acids I used a my 1'' hammer drill.

 

[jghall00]

I did something like this before. Instead of acids I used a my 1'' hammer drill.

Not an option for me. We get tested for emissions in my area. I also hate the smell of the exhaust when the cat doesn't work. We idle at softball practice when it's very hot or cold out, so it's embarrassing when the girls are warming up and your vehicle is the one funking up the entire parking lot.

 

[oil pan 4]

Not an option for me. We get tested for emissions in my area. I also hate the smell of the exhaust when the cat doesn't work. We idle at softball practice when it's very hot or cold out, so it's embarrassing when the girls are warming up and your vehicle is the one funking up the entire parking lot.

A one inch hole still catalyzes a large portion of the exhaust.
There's lots of people running around here with no catalytic converters. Drug addicts cut them off and the car owner replaces it with a pipe. It's cheaper and they won't get stolen again.