Q: The engine light is on and the code is P0420 - Catalyst System Efficiency Below Threshold Bank . What part do I need to fix it?

asked by on October 15, 2016

The engine light is on and we just want to know what the part needed to fix this issue. the code is P0420 - Catalyst System Efficiency Below Threshold Bank . However I dont know if its downstream or upstream.

My car has 130267 miles.
My car has an automatic transmission.

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While a number of things like a faulty oxygen sensor or exhaust leak can cause fault code P0420 to be set, the most common fault is the catalytic converter itself. However, as a replacement can be very expensive, your best be is to have a certified technician properly diagnose why code P0420 was set in the system.

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