P2A03 - O2 SENSOR CIRCUIT RANGE / PERFORMANCE BANK 2 SENSOR 1

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.

• Check Engine light on.
• Fuel efficiency is reduced.
• Engine experiences a general lack of power.
• Other DTCs are set.

The factors for which the P2A03 OBD2 error code is stored are:

• Oxygen Sensor 1 on bank 2, may be faulty.
• The circuit related to the O2 sensor may have bad wiring or connectors.
• The engine may be leaking exhaust.
• The Mass Air Flow (MAF) or Manifold Absolute Pressure Sensor (MAP) could be faulty.

The steps to resolve P2A03 OBDII fault code errors are:

• Consult the Technical Service Bulletins.
• Perform a scan of the vehicle to check if other DTCs are stored. If so, proceed to diagnose those codes first.
• Inspect the electrical system related to the Oxygen Sensor. In this check verify that the wires or connectors are not corroded, worn, or burned. Repair or replace any of these components as required. After making these repairs, clear the code.
• If the code returns, start the engine and once it reaches normal operating temperature, use the scanner to view the input data from the O2 Sensor. In the correct performance of this sensor, the data changes between 0.1 to 0.9 volts. If this is not the case, use a DVOM to check the resistance, voltage, and ground values of the circuit. If the results you get are out of specification, repair the bad wires, and if necessary replace the Oxygen Sensor.