P2631 Audi Front Air/Fuel Ratio Sensor Bank 2 Sensor 1 Circuit High Voltage
– Front Air/Fuel Ratio Sensor Bank 2 Sensor 1 circuit poor electrical connection
– Faulty Front Air/Fuel Ratio Sensor Bank 2 Sensor 1
The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The front A/F sensor transmits output voltage to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the front A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. The front A/F sensor (bank 2, sensor 1) has a built-in LABEL resistance to regulate the differences of the sensor characteristics. The PCM reads the resistance to regulate the difference properly. If the LABEL resistance (VLBLB 2 signal voltage) is a set value or more, the PCM detects a malfunction and stores a DTC.