Subaru Forester Outback Legacy Impreza Downstream Rear Oxygen Sensor 22690-AA900 234-4195

Subaru Forester, Outback, Legacy, and XV models use downstream oxygen sensor 22690-AA900 placed after the catalytic converter; monitors exhaust oxygen content and feeds ECU to optimize air-fuel ratio. Compatible with 22690-AA960, 22690-AA68A and other models. Replacement difficulty medium; labor about 0.5–1 hour; avoid damaging threads. If fuel economy increases, acceleration weakens, or check engine light is on, replace promptly.