Should i drive with a p0420 code or fix the catalytic converter now?

[Joseph23]

My 2016 Civic’s check engine light came on, and the code reader says it’s P0420 for catalyst efficiency below threshold. The car runs completely fine, no odd smells or loss of power. I’m just not sure if this is something I need to address immediately or if I can safely drive it for a while to see if it clears.

[AbigailMT]

I had P0420 on a Civic a few years back. The engine ran fine, no smell, no misfire, and the MIL stayed on for months. I drove it for about a week while I scheduled a diagnostic. It turned out the downstream oxygen sensor was flaky, not the catalyst itself, and replacing the sensor stopped the light.

[ChloeS]

I waited and watched for a while too, then finally got serious. The light stayed on, and the emissions test flagged the car. The shop found the downstream sensor and some wiring corrosion near it, swapped both, and the light stayed off after that.

[Oliver_M]

I’m not convinced we’re looking at the cat itself. A lot of times it’s a sensor or a small leak before the sensor that fools the code. If the car runs normal, it’s tempting to ignore, but I’d still get a quick check just to be sure.

[AvaJ]

Would you rather pay for a quick sensor swap now or wait and see if it self clears after a few days of steady driving?