on December 2, 2010, 5:04 pm, in reply to "Seat Ibiza 1.2L Catalyst Efficency P0420 lamp on"
Were they aftermarket or genuine dealer cats
Have you checked the gas readings at idle and fast idle, you need to eliminate the cat efficiency before you look further
Gas readings plus front and rear o2 sensor waveforms would be good. Have a look at fuel trims to see if its adding or taking away fuel
Peter
Message Thread 
Seat Ibiza 1.2L 2004 - MIL on, code P0420 Catalyst efficiency # - Malcolm Crosbie December 2, 2010, 4:34 pm
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