A P0420 diagnostic code on your 2017 Honda Accord indicates that the catalytic converter efficiency has fallen below acceptable levels. The 9th-generation 2017 Accord offers both 4-cylinder and V6 engines, each with distinct exhaust configurations.
2017 Accord Engine Options
- 2.4L 4-Cylinder: Single exhaust with one catalytic converter
- 3.5L V6: Dual exhaust with two converters - P0420 affects Bank 1
If you have the V6 and see P0420, it specifically refers to Bank 1's converter, not both.
Common Causes
- Converter Aging: At 7+ years, natural wear is expected
- Contamination: Oil, coolant, or fuel contamination
- O2 Sensor Failure: Faulty sensors causing false codes
- Exhaust Leaks: Air entering affecting measurements
- Past Engine Issues: Previous misfires damaging converter
- V6 Specific: Bank 1 issues may be isolated or system-wide