Catalyst effeciency

11-28-2007, 12:38 PM
Hey all,

My "check engine" light came on today, so I stopped and had the codes read. The code was: P0420 Catalyst effeciency below threshold (Bank 1). What exactly does that mean? What do I need to do to correct it??

2002 Elantra GLS, auto, 123k miles


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