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Dreaded P0420 bank 1 below threshold

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84K views 4 replies 4 participants last post by  burns_lots_of_oil  
M
#1 ·
Just installed an after market catalytic converter in March 23. Now getting the check engine light with the P code. Both bank1 and bank 2 sensors while the engine running are both in sync using the analyzer. No OEM converts out there and best after market was 650.00. Non California low emission unit

Is there any mods or converters that any one would recommend? It’s getting very hard to keep this 2012 with 300k going economically - coming up on 3rd timing belt and rollers that will be 500.+
 
#2 ·
The P0420 code signals a low catalyst system efficiency problem. This code suggests that the oxygen levels are below the desired threshold (Bank 1 or Bank 2), which most often results from problems with your car's exhaust or fuel systems. It can sometimes be tricky to diagnose.

Here are the three top fixes for the Honda / Acura P0420 error code.

  • Catalytic Converter Cleaner – Can be purchased at Walmart. I prefer the Dura Lube Catalytic Cleaner for around $20. I put it in the car with a half tank of gas. Sometimes you need to repeat this process if the light still doesn’t go off. If after two cleanings the problem still isn’t solved, move on to number 2# below.

  • Wash the Catalytic Converter – Remove the Catalytic Converter – Fill a large bucket with half cup of Dawn Dishwashing Liquid and hot water. Let soak for 10 to 15 hours occasionally sloshing the dishwater through the converter.

  • Clean and Modify the Oxygen sensor – Remove the Oxygen sensor and let soak in carb cleaner overnight, then modify the sensor by purchasing a spark plug non-fouler (2 for $20 at Walmart), drill out the bottom of the non-fouler with a ½” drill and then install the non-fouler between the sensor and converter.

Lastly, use a scan tool to clear the P0420 error code.

Using all three methods above will cost you less than $50 and will fix around 90% of the vehicles that come in with this error code. Home the helps.
 
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