P0430 fault code: low catalyst efficiency (Bank 2)
Plain-language definition
Catalyst System Efficiency Below Threshold Bank 2
What does it mean?
P0430 shows up on engines that have a separate catalytic converter for each bank of cylinders, such as many V and boxer engines. Bank 2 is the side without cylinder 1. The code means the efficiency calculated for the catalytic converter on this side has stayed below the threshold.
On petrol engines, the engine computer usually monitors each catalytic converter by comparing the oxygen (lambda) sensors in front of and behind it. As the catalytic converter loses its ability to store oxygen, the rear sensor's signal starts to look like the front one's and the calculated efficiency drops. If P0420 is stored too, a cause affecting both sides comes to mind, such as the engine burning oil or running rich for a long time.
Most of the time you won't feel any difference while driving; the check engine light may be the only symptom. If the catalytic converter has started to clog, you may notice less pulling power, and if its insides have broken up, a rattle from the exhaust.
How serious is it?
It's rated Warning: it indicates that the Bank 2 catalytic converter isn't cleaning the exhaust gases well enough. If a problem that damages the catalytic converter is still there, a new one can be affected the same way.
Severity is a guide; if the warning light is flashing or you notice symptoms while driving, have the car checked at a workshop.
Common general causes
- Aged catalytic converter, or one that has lost its efficiency
- Misfires or a rich mixture in the Bank 2 cylinders
- The engine burning oil or coolant
- Bank 2 oxygen sensor after the catalytic converter giving wrong readings
- Exhaust leak near the oxygen sensors
The list shows general causes; a workshop finds the actual cause on your car with a check.
Definitions by make
Some manufacturers record the same code under their own wording:
- Honda
- Front Bank Catalyst System Efficiency Below Threshold (Bank 2)
- Mitsubishi
- Catalyst System Efficiency Below Threshold (Bank 2); Catalyst deterioration 2
- Volkswagen
- Catalyst System Low Efficiency Bank 2
Related codes
How does it appear in the 2dakika report?
Catalyst System Efficiency Below Threshold Bank 2
If the code is read as a confirmed (stored) fault, the report shows it with the "Warning" severity; in pending or past records, codes that don't request the warning light and aren't critical appear as "Info". If the engine computer stored them, the conditions when the fault was recorded (engine temperature, rpm, speed) are shown too.
Read this code with the OBD-X1, and clear it from the app after the repair.
Clearing the code doesn't fix the fault; if the problem persists, the code comes back.