Hondata

i recently installed the k-series reflash and had the error code P0420: catalyst system efficiency below threshhold pop up
i also discovered that my car is running rich by checking the spark plugs and i know that 02-04 rsx already do run rich but i dont think this is supposed to set off an error code.
so my question is how can i correct this or is this expected?

What vehiclele is this and what has been done to the car?

i have an 2004 rsx type s with a cai
i reset the code and so far it hasnt popped up under normal driving conditions so im thinking that its only triggered in higher rpms maybe around the new vtec point

So you cleared the code adn it has not come back?

i cleared the code and it came back today during normal driving conditions

The next step is to follow the troubleshooting steps in the Helms manual for that specific error code.

I looked up what to do under a P0420 code in the helms manual but you need the scan tool to do the check and I dont have one
but when i took my car to my mechanic he said the code is most likely caused by the car running too rich.

is it possible that the stock exhaust is too restrictive and setting off the error code?