Being I was a Mopar tech for years but am retired now as stated it has to meet certain driving parameters before it will run and pass the test. The DRBIII tool we had at the Mopar dealer would give us a screen that showed what parameters needed to be met and would show when they were met when we drove it to the right parameters and the DRBIII would even show if the test was running. Are you sure there are no other codes or secondary indicators ? Course the catalast moniter has to have the up and down stream 02's working right to run the test. The PCM also uses the downstream 02 readings to help set the goal of the upstream 02. I used to be able to see if the upstream 02 goal was set in the DRBIII scanner as it may not run the test if the upstream 02 sensor goal is not set. I used to have the info on what was needed to make the test run as it has to have the eng on for so much time and be driven above a certain mph for so long and above a certain eng temp and so on. Sorry as I dont remember all the test parameters it needs to meet off the top of my head. Ron