BMW 1 Series Rear Oxygen Sensor 11787589122 0258010239 Ready for installation, immediate use. Engine performance restoration.

When BMW 1 Series shows idle instability, unusual fuel consumption, or the dashboard lights up "Check Engine" (e.g., P0138/P0140), the downstream oxygen sensor may be aging and unable to monitor exhaust oxygen accurately. This sensor feeds catalytic converter exhaust data to the ECU to help adjust air-fuel ratio; OEM 11787589122 (compatible 0258010239); fits BMW 1 Series (E81/E82/E87/E88) and some 3 Series (E90/E91). Install on cold engine, use a dedicated wrench to avoid thread damage, and ensure sensor wiring does not contact high-temperature exhaust areas.