P0420 Code Coming On And Off

[DOAJ20]

I have a 2016 mustang gt with 138k miles, I’ve had issues with a P0420 code for about a year now never bothered with it because it was constantly back and forth. I would have the code for a week or 2 then it would disappear for awhile then come back, it was never consistent. What’s concerning me is that now it come on back and forth but more often and I’ve always noticed the car at idle tends to shake pretty bad not all the time during idle but here and there it feels like the car wants to die then comes back to normal. Anyone have any similar issues or just looking for direction to go with this because it’s just annoying. Thank you !!

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[robvas]

Failing cat?

 

[DOAJ20]

Failing cat?

So if it is a failing cat, this may be a dumb question I don’t have alot of experience with a failing cat, but the only option would be to purchase it brand new and replace it correct ?

 

[robvas]

So if it is a failing cat, this may be a dumb question I don’t have alot of experience with a failing cat, but the only option would be to purchase it brand new and replace it correct ?

Or remove them (and/or install headers)

 

[ORRadtech]

It could just be a failing O2 sensor. I'd suggest putting the car on a bidirectional scan tool and getting some more solid information. Checking O2 heater function and performance along with fuel trims.
O2 sensors are less expensive than the cats and, if it turns out to be a bad cat(s), you'll want to replace them anyway. Don't cheap out on sensors, go to Ford (or a reputable parts store) and get OEM sensors.
Also, although far from guaranteed, there are fuel additives that may help to clean and prolong cat life.

 

[DOAJ20]

It could just be a failing O2 sensor. I'd suggest putting the car on a bidirectional scan tool and getting some more solid information. Checking O2 heater function and performance along with fuel trims.
O2 sensors are less expensive than the cats and, if it turns out to be a bad cat(s), you'll want to replace them anyway. Don't cheap out on sensors, go to Ford (or a reputable parts store) and get OEM sensors.
Also, although far from guaranteed, there are fuel additives that may help to clean and prolong cat life.

I appreciate it man!

 

[robvas]

Swap the sensors from one side to the other to see if the code follows the sensor

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