Set Condition
WARNING: This page is about a different car, the 2014 Fiat 500c and 2014 Fiat 500. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) monitors the downstream O2 Sensor. If the PCM does not detect a rich to lean switch within a specific time during a decel fuel shutoff event, the monitor will fail. One trip fault. Three good trips to turn off the MIL.