Possible causes
– Rear Air/Fuel Ratio Sensor Bank 1 Sensor 1 harness is open or shorted
– Rear Air/Fuel Ratio Sensor Bank 1 Sensor 1 circuit poor electrical connection
– Faulty Rear Air/Fuel Ratio Sensor Bank 1 Sensor 1
– Rear Air/Fuel Ratio Sensor Bank 1 Sensor 1 circuit poor electrical connection
– Faulty Rear Air/Fuel Ratio Sensor Bank 1 Sensor 1
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P2251 Description
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.
P2251 Information for specific makes
P2251 ACURA
P2251 DODGE
P2251 HONDA
P2251 HYUNDAI
P2251 SCION
P2251 LEXUS
P2251 TOYOTA
P2251 DODGE
P2251 HONDA
P2251 HYUNDAI
P2251 SCION
P2251 LEXUS
P2251 TOYOTA