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Discussion Starter · #1 ·
A check engine light appeared with engine code P0420 (Catalyst System Efficiency Below Threshold (Bank 1)). Unfortunately, no other errors appeared pointing to a specific oxygen sensor so it could be many things.

Has anyone else seen this code, and if so did you replace an oxygen sensor or the catalytic converter?

Also, does anyone know the dealership cost to replace a catalytic converter?

For reference, I have 145k odometer, which doesn't seem like a lot...
 

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Discussion Starter · #3 ·
I'm considering it.

I found a few comments saying a dealer Cat is $4k, and a new tranny is $4k (tranny is still running smooth but I expect it will die around 200k). The SUV is only worth $8k, soooooo might as well as get rid of it.

I'm going to swap the oxygen sensors with bank 2 to see if the code moves as well.
 

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Discussion Starter · #4 ·
I swapped the first O2 sensors, hoping the error will follow to bank 2.. Then I will know if it's an upstream sensor issue.

Bank 1 downstream sensor is nearly impossible to access.
 

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Discussion Starter · #5 ·
Engine light popped back on shortly after resetting.

I was heading on a T-Day road trip so I added Lacquer Thinner (see Video below), than drove 130 miles with the engine light on the entire time.

The next morning I started the car and no light. Drove it around for a few days, then home (another 130 miles), and the light never came back. Success!!!!!

Not sure if it's the lacquer thinner or (a guess) the cats don't get warmed up enough to clean themselves driving kids around town, school pickup (no more work commute), etc…. Either way I'm hopeful this will hold for a while.

 

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A check engine light appeared with engine code P0420 (Catalyst System Efficiency Below Threshold (Bank 1)). Unfortunately, no other errors appeared pointing to a specific oxygen sensor so it could be many things.

Has anyone else seen this code, and if so did you replace an oxygen sensor or the catalytic converter?

Also, does anyone know the dealership cost to replace a catalytic converter?

For reference, I have 145k odometer, which doesn't seem like a lot...
Yes I have experienced the engine code P420 coming on a few times over the last 2 years. I have a 2015 QX60 Hybrid with 156K miles. My mechanic tested the CAT, the sensors were fine and suggested I add CataClean to my gas tank. Sold in Auto stores and online. I did it and the light went off. I have had to do it 3 times over 2 years and not had a problem, and pass PA state emissions inspection with no issues. FYI the first time it happened I took it to the dealer and they wanted to replace the whole thing!
 
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