P0420 on Honda vehicles
39 owner complaints filed with NHTSA about Honda vehicles mention P0420 (Catalyst System Efficiency Below Threshold Bank 1) - across 6 models. Below is where it shows up, by model and year.
Can you drive with it? Yes - the car remains driveable. Fix it before emissions testing: this code is an automatic inspection failure in most states.
Symptoms, likely causes in order and realistic repair costs are on the main P0420 page - they do not differ much by brand. This page shows what is specific to Honda: which models and years actually report it.
Honda models reporting P0420
The number next to each year is how many NHTSA complaints for that car mention P0420. Owners rarely quote trouble codes when complaining, so real occurrence is many times higher - use these numbers to compare years, not as totals.
What Honda owners report
“2019 Honda Odyssey purchased new and one owner. Vehicle's VIN didn't fall under Honda TSB # 21-010 despite vehicle suffered a known defect pattern so Honda denied assistance soley due to VIN exclusion. Sequence: emissions system warning, P0420, injector failure diagnosis, consequential catalyst failure after injector malfunction.”2019 Honda Odyssey · May 2026
P0420 on other makes
Makes with enough NHTSA reports of P0420 for their own page.
Counts are NHTSA owner complaints whose text mentions P0420 - owner-reported and unverified. Always confirm with a diagnosis of your specific vehicle.