Camaro zl1 2020 code saying p0420?

2020 CHEVROLET CAMARO
37,000 MILES • 6.2L • V8 • TURBO • 2WD • MANUAL
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SOLO987
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Well I have been having problems with knock sensors. On both bank 1 and 2 and now I got a code saying p0420. And I have headers and a cold air intake on it.
Sep 5, 2025 at 5:33 PM
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STRAILER
  • ✓ASE Certified Mechanic
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  • ASE Certified Mechanic
Did you remove the catalytic converters? if so this will be the reason for the trouble code:

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

Please let me know.
Sep 6, 2025 at 4:29 PM
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SOLO987
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Yeah I did. Im running kooks headers
Sep 6, 2025 at 4:34 PM
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STRAILER
  • ✓ASE Certified Mechanic
  • 54,832 POSTS
  • ASE Certified Mechanic
If you don't have cats you will have this code and the engine will not run at optimum performance. Believe it or not the engine is made to run at the best performance from the factory. Unless you plan a bunch of expensive engine and computer work is it best to leave it stock.
Sep 7, 2025 at 8:54 AM
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