Thanks guys!

The car was imported from the U.S. so I think it's programmed for O2 sensor input. As Shogun said,maybe the cat section may have been ripped off at some time with the owner not knowing the consequence of running without a proper O2 sensor.

Mike, thanks for the picture, it will surely help. I'll print it and bring it to a muffler shop together with the new sensor.

thanks again. I'll let you all know how it goes.