P0420 code on Astro
I have a 2002 Astro 2WD with 137k on it, original owner. The past few days it'* been throwing a P0420 code, "Catalyst System Efficiency Below Threshold (Bank 1)." I have an OBD II reader and have been resetting the code, but it'* come back on now 3 times.
Does anyone know what exactly would trip this particular code? I had the cat replaced less than 20k ago due to an unrelated problem. The 3-stud exhaust flange at the rear end of the cat is missing one of its studs (broke off), and I haven't gotten around to drilling out the remains and replacing with a nut and bolt yet as it'* freakin cold out and snowy. Would the (very minor) leak that'* resulting from the missing stud cause this code?