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p0420 code after replacing 02 sensors, cat, turbo and plugs

10K views 10 replies 8 participants last post by  Blasirl 
#1 ·
Hello'
Hoping I can get some advice..i have a 2011 cruze 1.4 turbo with 153,xxx miles and cant get rid of this p0420 code. Ive had the up and downstream 02 sensors replaced, ive had the cat replaced and ive replaced the turbo. I dont know what could be throwing this code..im also getting the u0100 code which is ecm/pcm lost communication. Any insight would be helpful.
Thanks
 
#10 ·
It depends on how efficient the replacement cat is and how sensitive the rear 02 sensor/ECM is. Older vehicles you could get away with a cheap universal cat, but newer ones have to be good quality. Can't go wrong with OEM here. Otherwise you need a higher end aftermarket replacement. Also, make sure you fixed the problem that caused the original cat to fail as a new one won't last if the engine is still running very rich.
 
#11 ·
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: https://www.obd-codes.com/p0420
 
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