Diagnostic knowledge

P0420 vs P0430

P0420 and P0430 have the same catalyst-efficiency definition, with a different bank. Compare the scoped reference wording before using either code.

Reference familyP0420 · Bank 1P0430 · Bank 2
BMWCatalyst System Efficiency Below ThresholdCatalyst System Efficiency Below Threshold
Continental Synerject Easy UCatalyst System Efficiency Below Threshold Bank 1—
FordCatalyst System Efficiency Below Threshold (Bank 1)Catalyst System Efficiency Below Threshold (Bank 2)
Acura / HondaCatalyst System Efficiency Below ThresholdFront Bank Catalyst System Efficiency Below Threshold (Bank 2)
Genesis / Hyundai / KiaСистема катализатора, эффективность ниже порогового уровня (ряд 1)—
ISUZUCatalyst operating efficiency below threshold - Bank 1—
Dodge / MitsubishiCatalyst System Efficiency Below Threshold (Bank 1); Catalyst deteriorationCatalyst System Efficiency Below Threshold (Bank 2); Catalyst deterioration 2
Infiniti / NissanCatalyst System Efficiency Below Threshold (Bank 1)Catalyst System Efficiency Below Threshold (Bank 2)
Generic OBD2Catalytic converter system, bank 1 - efficiency below thresholdCatalytic converter system, bank 2 - efficiency below threshold
Belgee / Geely / ProtonCatalyst System Efficiency Below Threshold (Bank 1)Catalyst System Efficiency Below Threshold (Bank 2)
Dacia / RenaultНизкая эффективность каталитической системы C-029—
GAC / Lexus / ToyotaCatalytic Converter System Bank 1 Efficiency Below ThresholdCatalytic Converter System Bank 2 Efficiency Below Threshold
УАЗЭффективность нейтрализатора ниже допустимой нормы—
Audi / Jetta / MAN / Seat / Skoda / VolkswagenCatalyst System Low EfficiencyCatalyst System Low Efficiency Bank 2

Bank 1 is the side containing cylinder 1. Bank 2 is the other side on V or flat engines; inline engines have only Bank 1. For exhaust oxygen sensors, Sensor 1 is upstream, closest to the engine; Sensor 2 is downstream, after the catalyst.

P0420 · P0430 · P0135 · P0141 · Brand references · Pending, stored and permanent codes

What is the difference between P0420 and P0430?

P0420 and P0430 have the same catalyst-efficiency definition, with a different bank.

What does P0420 mean?

Catalytic converter system, bank 1 - efficiency below threshold

What does P0430 mean?

Catalytic converter system, bank 2 - efficiency below threshold

Reference-family membership is not proof that a code applies to every listed ECU or vehicle. Runtime-ready definitions are not physical-vehicle validation. Unavailable readings must not be treated as zero. App and hardware sale availability must be checked separately.