Help! please! Cat Monitor Wont Run

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I have a 2005 Motorhome on a Chevy Express 3500 chassis with the 6.0 liter. It began throwing the OBDII Code for a bad O2 sensor (bank 1 Sensor 2). I replaced the sensor and cleared the codes. I ran the vehicle through the drive protocol provided by chevy to run all the monitors. (I have now run the protocol more than a dozen time and have put on about 1000 miles) The sensor monitor ran and did not kick an O2 sensor error. No error codes were thrown but it wont run the Cat Monitor. In CA it wont pass smog unless the cat monitor runs. Any ideas? Could the sensor I put in not throw a code (operates between .5 and 1 volt) but not be working well enough to trigger the cat monitor to run? I noticed that there are about 4 different AC delco part numbers for O2 sensors for that vehicle.