i have a pr3 ecu and when i start it up and run it, no cel on but the light comes on sometimes but it has no pattern wat so ever. mad weird.. when it comes on, it blinks two long and three short and then two short so i searched and came up wit the second o2 senor but i have both there.... wats code 23? or wat do u think is doin this??? thanks

 

I think 23 is knock sensor.

 

If the second O2 is on the car, make sure its actually hooked up to the ecu. If it is wired in correctly, then i would guess that u need a new second O2.