2004 Toyota Siena P0420 Code: Urgent Engine Noise and Check Engine Light Issue

Model: 2004 Toyota Siena Fault Code: P0420 Posted: 2018-10-27 15:58

My 2004 Toyota Siena recently triggered the check engine light, displaying fault code P0420. This is accompanied by a noticeable increase in engine noise—particularly at higher RPMs—though no unusual performance issues are present during idle. The sound is louder than normal and seems to worsen under load. I'm concerned about how urgent this issue is, especially since I don't have immediate access to a repair shop. Can anyone confirm if P0420 on a 2004 Toyota Siena indicates a serious problem or just a minor emission system issue?