Chevrolet Cruze Forums banner

P0420 won't go away what should I do

651 Views 1 Reply 2 Participants Last post by  Blasirl
So I have a 2012 Chevy Cruze Lt 1.4 I'm having trouble with this code I replaced the O2 sensors I replaced the front catalytic converter and the rear catalytic converter I totally don't know what's wrong with my car when I went to a local mechanic he said it was my front catalytic converter I replaced it but the check engine light kept coming on with that code GM they told me that it was my rear catalytic converter said they saw a crack near my flex pipe but it didn't penetrate to do any damageb from what I saw once I replaced it can anybody give me any type of help I really don't know what I should do my check engine light just keeps coming on?
1 - 2 of 2 Posts
So I have a 2012 Chevy Cruze Lt 1.4 I'm having trouble with this code I replaced the O2 sensors I replaced the front catalytic converter and the rear catalytic converter I totally don't know what's wrong with my car when I went to a local mechanic he said it was my front catalytic converter I replaced it but the check engine light kept coming on with that code GM they told me that it was my rear catalytic converter said they saw a crack near my flex pipe but it didn't penetrate to do any damageb from what I saw once I replaced it can anybody give me any type of help I really don't know what I should do my check engine light just keeps coming on?
Go to a shop that specializes in emissions' , not a parts replacer.


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

Leaded fuel was used where unleaded was called for (unlikely)
A damaged or failed oxygen / O2 sensor
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
Failed or underperforming catalytic converter (likely)
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
Read more at: P0420 Catalyst System Efficiency Below Threshold
See less See more
1 - 2 of 2 Posts
Top