The O2 sensors indicate the PCM the amount of oxygen that is in the exhaust, which is used to control and determine the air/fuel mixture. If there is a high oxygen content, the mixture is lean. Contrary to this, a rich mixture will be obtained. The Oxygen Sensor has a cycle every second. It provides the PCM with a voltage that varies between 0.2 to 0.8 for a lean or rich mixture respectively.
The DTC P2098 OBDII indicates that the Powertrain Control Module (PCM) detects through the Oxygen (O2) Sensors, a lean condition in the fuel trim system, which is located at the rear of the Catalytic Converter (TWC).