Which trouble codes do owners report?

P0420 Catalyst System Efficiency Below Threshold is the largest group at 64, out of 1,459 complaints.

Trouble codes owners quote in complaints about this part. P0420 Catalyst System Efficiency Below Threshold: 64; P0430 Catalyst System Efficiency Below Threshold: 23.

The code owners quote most is P0420. Read your own code from a scan and give the shop the exact code, not only "the light is on".

Source: NHTSA owner complaint files · downloaded 2026-10-05

Data and chart by CalcScrape: Catalytic Converter Replacement Cost Calculator