darkstar1026 Posted May 22, 2013 Report Share Posted May 22, 2013 As the title states, my truck is throwing this code and it says "catalyst sys efficiency threshold (bank 1)". Is this a O2 sensor and if so where is it located? Is there not four sensors on our trucks? My truck is also throwing code P0101 and I have a MAF sensor coming in. Quote Link to comment Share on other sites More sharing options...
diggerdan11 Posted May 22, 2013 Report Share Posted May 22, 2013 They the P0420 code is your 02 sensor. Yes there are 4 02 sensors 2 in front and 2 behind the cats. It is possible you could have plugged Cats. That happend in my Tahoe and i through the same code Quote Link to comment Share on other sites More sharing options...
darkstar1026 Posted May 22, 2013 Author Report Share Posted May 22, 2013 Which O2 sensor is bank 1? Is that driver side before the cat? Should I pull it out and clean it? Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted May 22, 2013 Report Share Posted May 22, 2013 Drivers side post cat(rear 02) is the sensor that code pertains to, bank 1 sensor 2..... Quote Link to comment Share on other sites More sharing options...
diggerdan11 Posted May 22, 2013 Report Share Posted May 22, 2013 Drivers side post cat(rear 02) is the sensor that code pertains to, bank 1 sensor 2..... ^ this. Sorry I should have explained that in my last post Quote Link to comment Share on other sites More sharing options...
darkstar1026 Posted May 22, 2013 Author Report Share Posted May 22, 2013 Thank you gentlemen Quote Link to comment Share on other sites More sharing options...
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