Postby smj999smj » Wed Nov 12, 2014 11:49 am
The oxygen sensors have built-in heater elements to heat-up the sensors. Assuming they didn't damage the wires or bend a pin in the harness connector when they replaced the catalytic converter, you likely have a broken heater element in the sensor, meaning you would need to replace the sensor, itself. B2S2 would be the rear sensor on the left, or driver's side. It would be NTK oxygen sensor #24244. I prefer to stick with NTK as they are the OEM manufacturer of Nissan sensors, but Denso is pretty good, too. I usually get them from Rockauto.com as their prices are usually the lowest.