Eml p0420

[HawkSTI]

I keep getting an eml thrown up. 

The code I'm getting is P0420 

"catalyst system efficiency below threshold (bank 1)"

any one else had this or know exactly what it means? 🤔

[mattiekane]

I believe that's triggered if the pre and post cat O2 sensors reading are similar(cat appears to not be doing it's job)

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[HawkSTI]

7 minutes ago, mattiekane said:

I believe that's triggered if the pre and post cat O2 sensors reading are similar(cat appears to not be doing it's job)

Sent from my HTC One M9 using Tapatalk
 

There's one in the downpipe and one between the downpipe and centre section on the hawks I think. Any way of telling which one needs replacing?

[mattiekane]

What are you using to code read?

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[mattiekane]

https://allwheeldriveauto.com/subaru-check-engine-light-and-code-p0420-explained/

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[HawkSTI]

@mattiekane torque pro 👍