OBD (On-Board Diagnostics) Diagnostic Trouble Codes, commonly known as DTCs, are standardized fault codes generated by a vehicle's electronic control modules when a malfunction is detected.

P0420 is a common OBD-II trouble code indicating that the catalytic converter on Bank 1 is no longer operating efficiently enough to meet emissions standards.

P0111 is a generic OBD-II diagnostic trouble code indicating that the Engine Control Module (ECM) has detected an Intake Air Temperature (IAT) sensor signal that is outside the expected operating rang···