# P0431 & P0421 Cat Below Efficiency Threshold FIX



## samick123 (Feb 28, 2011)

1. Replaced Spark Plugs
2. Replaced Evap Purge Valve.
3. Allowed (EVERY TIME) my car to do its 30 second startup procedure upon cold start

Done. Clear for almost a week now.


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## WouldaShoulda (Aug 7, 2013)

Don't Jinx it!!


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## samick123 (Feb 28, 2011)

*It's still off*

It hasn't even flickered.

Still off. Although my alternator need replacing, cat codes- all emissions codes actually, are still clear.


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## sellingthewind (Jan 28, 2008)

Nice! How is this holding up?


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