p0420 code states Catalyst deficiency below threshold, what would be main cause of code?

Question

2004 chevy Malibu 2.2L ecotech

Answer 1

This means the catalytic converter is not working properly due to one or more possible causes below

Possible causes

- Three way catalyst converter Bank 1

- Exhaust tube

- Intake air leaks

- Fuel injectors may be faulty

- Fuel injector leaks

- Spark plugs may be faulty

- Improper ignition timing

- Powertrain Control Module (PCM)