Po420

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. [emoji6] https://uploads.tapatalk-cdn.com/201...31a2789ce1.jpghttps://uploads.tapatalk-cdn.com/201...292fa59c37.jpg

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Did you see this thread?

Thread: p0420 code

Quote:

---

P0420 Error Code: Catalyst System Efficiency Below Threshold (Bank 1)

A code P0420 may mean that one or more of the following has happened:

•Leaded fuel was used where unleaded was called for
•A damaged or failed oxygen sensor (HO2S)
•Downstream oxygen sensor (HO2S) wiring damaged or connected improperly
•The engine coolant temperature sensor is not working properly
•Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe
•Retarded spark timing
•The oxygen sensors in front and behind the converter are reporting too similar of readings
•Leaking fuel injector or high fuel pressure
•Cylinder misfire
•Oil contamination

---

Thread: Replaced Cat, but P0420 code

Did you see this thread?

Thread: p0420 code

Quote:

---

P0420 Error Code: Catalyst System Efficiency Below Threshold (Bank 1)

A code P0420 may mean that one or more of the following has happened:

•Leaded fuel was used where unleaded was called for
•A damaged or failed oxygen sensor (HO2S)
•Downstream oxygen sensor (HO2S) wiring damaged or connected improperly
•The engine coolant temperature sensor is not working properly
•Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe
•Retarded spark timing
•The oxygen sensors in front and behind the converter are reporting too similar of readings
•Leaking fuel injector or high fuel pressure
•Cylinder misfire
•Oil contamination

---

Thread: Replaced Cat, but P0420 code

Hi MetroMPG, yeah i did read thru those thread. So as 1 of the diagnose i did my oxygen sensor.
How does the graph above show u? Does it look like a bad 02 sensor? Or bad cat?


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