A P0420 diagnostic code on your 2023 Toyota Sienna indicates that the catalytic converter efficiency has dropped below acceptable levels. The 2023 Sienna continues with the hybrid-only powertrain.
2023 Sienna Hybrid
The 2023 Sienna uses a 2.5L 4-cylinder hybrid system (245 hp combined). All Siennas are hybrids with single exhaust bank configurations.
P0420 on Newer Vehicle
A 2023 Sienna showing P0420 is relatively early for converter failure:
- O2 Sensor Issues: More likely than converter failure
- Hybrid System Issues: May affect converter monitoring
- Exhaust Problems: Loose connections possible
Warranty Coverage
A 2023 Sienna should be under full warranty.