Q: P0420 OBD-II Trouble Code: Catalyst System Efficiency Below Threshold (Bank 1)

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Hi. The engine light it's turn on and we find this code P0420 what I can do? We open the lambda sensor and put in catalytic converter some dpf cleaner that recommend to me one shop. I press to much after this the car but the light it's not back. Maybe will be after

My car has 136000 miles.
My car has a manual transmission.

Hi there:

the P0420 OBD-II Error code indicates that the catalytic converter is not working as efficiently as it is intended. If the voltage of the downstream oxygen sensor decreases, and begins to fluctuate like the upstream oxygen sensor, it means that the oxygen levels are too high. Adding the "additive" is a quick fix but usually only lasts a few weeks, so you might want to have a mechanic replace your catalytic converter as soon as possible.

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