Theory of Operation
WARNING: This page is about a different car, the 2011 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The Smart Oxygen Sensor Module (Smart O2 Module) is a smart device that receives information via the J1939 Datalink from the Powertrain Control Module (PCM). It provides the PCM with the oxygen concentration signal. It also performs its own diagnostics and reports failures back to the PCM over the J1939 Datalink.