The Oxygen Sensor (O2) is a key component in the vehicle’s emissions system. It is designed to monitor the oxygen present in the car’s exhaust, it also verifies the good work of the Catalytic Converter (TWC) and its efficiency level. These sensors detect whether the vehicle’s engine is running with an excessively rich or excessively lean air/fuel mixture when part of the oxygen is burned, once it passes through the exhaust. The information collected by the O2 Sensor is sent to the car’s computer to make adjustments to the fuel metering and timing to obtain an optimum air/fuel mixture.
When the P2A03 OBDII diagnostic code is set, it means that the PCM (Powertrain Control Module) has found a malfunction in the Oxygen Sensor number 1 circuit of bank 2. Specifically, the circuit of this sensor has not been activated as expected for a certain time.