# Compare OBD codes and concepts

Source: https://obdlens.com/compare/
Last built: 7508d481ba6c398f25ed

Compare catalyst codes, oxygen-sensor positions, engine banks and OBD reference scope. Use each comparison’s scoped reference wording and vehicle service information to interpret the definitions.

- [P0420 vs P0430](https://obdlens.com/compare/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.

- [Upstream vs downstream O2 sensor](https://obdlens.com/compare/upstream-vs-downstream-o2-sensor/)For exhaust oxygen sensors, Sensor 1 is upstream, closest to the engine; Sensor 2 is downstream, after the catalyst. Confirm the exact sensor layout in the vehicle’s service information.

- [Bank 1 vs Bank 2](https://obdlens.com/compare/bank-1-vs-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.

- [OBD1 vs OBD2: reference scope](https://obdlens.com/compare/obd1-vs-obd2/)OBD Lens publishes generic OBD2 and manufacturer reference families. Use the reference namespace and vehicle profile to establish the scope of a definition.

## What is the difference between P0420 and P0430?

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

## Which oxygen sensor is upstream?

Sensor 1 is upstream, closest to the engine.

## What is Bank 1?

Bank 1 is the side containing cylinder 1.

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.

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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.