What P0430 means
Catalyst System Efficiency Below Threshold (Bank 2)
How to diagnose
- Read freeze frame data. When P0430 set, your ECU snapshotted every sensor at that moment. This tells you what the car was doing when the fault triggered — RPM, load, coolant temp, throttle position, fuel trims. Almost always enough info to figure out the cause without further testing.
- Check for related codes. If you have P0430 plus other codes, fix the earliest one in the chain first — a single root cause often triggers multiple codes.
- Cheap fixes first. For most codes, the order is: inspect connectors + wiring (free), check for vacuum leaks (cheap), replace sensor (moderate), replace mechanical part (expensive). Follow that ladder before dropping money on parts.
Manufacturer-specific descriptions
Different manufacturers use P0430 for slightly different failure modes:
| AUDI | Defective Catalytic Converter, Internal engine damage resulting in high oil consumption and or a leaking Head Gasket has damaged the Catalytic Converter |
| BMW | Catalyst System Efficiency Below Threshold |
| FORD | Catalyst System Efficiency Below Threshold (Bank 2) |
| HONDA | Front Bank Catalyst System Efficiency Below Threshold (Bank 2) |
| MITSUBISHI | Catalyst System Efficiency Below Threshold (Bank 2); Catalyst deterioration 2 |
| NISSAN | Catalyst System Efficiency Below Threshold (Bank 2) |
| VOLKSWAGEN | Catalyst System Low Efficiency Bank 2 |
Read P0430 on your own car
DIY Fix My Car reads P0430 plus 25,000+ other DTC codes with manufacturer-specific descriptions. Includes freeze frame data, likely fix parts, and AI mechanic chat. Download free.