2018 CR-V Check Engine Light - P0420 Code

ClearTheCode guidance (Honda · Diagnostics & codes)

Summary: For 2018 CR-V Check Engine Light - P0420 Code, work through these steps on your 2016+ vehicle:

1. Confirm the symptom — note when it happens (cold start, highway, after fuel fill, etc.).
2. Scan codes — save all pending/stored DTCs; don't clear until you've recorded them.
3. Check TSBs & recalls — look up your VIN for open campaigns and known fixes.
4. Inspect the obvious — related fuses, connectors, fluid level, and recent repairs.
5. Test the common fix — follow model-specific service procedures; one change at a time.
6. Escalate if needed — burning smell, no brakes, overheating, or stalling in traffic → shop visit.

Owner reported: Hey everyone,

My Check Engine Light (CEL) came on in my 2018 Honda CR-V EX-L a couple of days ago. I borrowed a scanner and pulled the code, and it's showing P0420: Catalyst System Efficiency Below Threshold (Bank 1).

The car seems to be running perfectly fine, no noticeable loss of power, no strange noises, and fuel economy hasn't changed. I'm a bit stumped since there are no obvious symptoms. …

This is educational guidance, not a substitute for hands-on diagnosis.