Hello all,
I have Aveo 1.4 auto LS, previously i had an error code P0300 misfire. Went to workshop got it fixed by replacing the ignition module which is faulty.
Soon after i've another error code P0420 so i did a diagnose by Torque app for oxygen sensor.
Did a read up on the web P0420 is cause by catalytic converter not performing effeciently. My plan is to check for other possible cause before jumping into conclusion.

Do need help & advice for possible causes and experience from other who ever encounter this problem.

Below is a screen shot of my O2 sensor. Kindly advice.

1st pic showing reading of warm up engine @ 2k to 2.5k rpm

2nd pic showing reading at idle rpm

Thank you in advance.

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