P2251 HONDA - Rear Air/Fuel Ratio Sensor Bank 1 Sensor 1 VS Line High Voltage
- Rear Air/Fuel Ratio Sensor Bank 1 Sensor 1 circuit poor electrical connection
- Faulty Rear Air/Fuel Ratio Sensor Bank 1 Sensor 1
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits a signal to the powertrain control module (PCM), and it enables overall feedback control. The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. When the VSB1 terminal voltage is more than a specified value for a predetermined time, the PCM detects a malfunction and stores a DTC.