To replace Bank 1 Sensor 1 (the upstream oxygen sensor) on a Subaru Legacy, first, ensure the engine is cool and disconnect the battery. Locate the sensor on the exhaust manifold, then use a suitable oxygen sensor socket or wrench to unscrew it. Install the new sensor by threading it in by hand, then tighten it securely without over-torquing. Finally, reconnect the battery and clear any diagnostic trouble codes if necessary.
Subarus number their cylinders differently, perhaps because they're first and foremost a Right Hand drive car in their native Japan. Bank #1 is the passenger side on an American Subaru, Bank #2 is driver side. So if you throw an ECM code of P0051 (Oxy sensor heater problem - Bank#2, Sensor #1) you probably have to replace the Oxygen sensor on the driver's side of the car. Sensor 1 is the sensor BEFORE the catalytic converter. You'll have to get under the car to replace it, but it typically only involves unscrewing the old sensor, replacing it with the new, then connecting the wire for the new sensor in the same place as the old connection.
same way you replace any sensor.
$49.99
driver side bank 1 before cat
Inspect the wiring to the bank 2 knock sensor, if the wiring looks okay replace the bank 2 knock sensor.
Unplug then unscrew the old one. Screw the new one in and plug it into the wiring harness. Special sockets that will help you to remove the oxy sensor are available for loan at many auto parts stores.
Replace bank one O2 sensor
usually bank 1 is the bank with # 1 cylinder in it and sensor # 1 is the front o2 sensor(usually in the manifold). You will need a O2 sensor socket or a 22mm wrench or deep socket.
On a 2004 Subaru Forester, the location sensor bank 1 sensor 1 refers to the upstream oxygen sensor located before the catalytic converter on the engine's exhaust system. This sensor is part of the vehicle's emissions control system and plays a crucial role in monitoring the air-fuel mixture for optimal engine performance. It is typically found on the exhaust manifold or in the front pipe near the engine.
On a 2005 Subaru Outback, Bank 2 Sensor 1 is located on the exhaust system, specifically on the passenger side of the engine. It is positioned upstream of the catalytic converter, before the exhaust gases enter the catalytic converter. This sensor measures the oxygen content in the exhaust gases to help optimize engine performance and emissions.
O2 sensor circuit bank 1 sensor 2 no activity. Check the wiring and connections to bank 1 sensor 2 O2 sensor, if all looks good replace the sensor.
Replace it. Sensor 2 is the one AFTER the catalytic converter.