How to Replace the Oxygen Sensor on a BMW 740i

1. Pop the hood of your 740i and locate the rear exhaust manifold (found on the rear of the engine). The oxygen sensor will be sticking off of the back of the manifold with a wire running to it.
2. Disconnect the wiring harness and use the oxygen sensor wrench to unscrew the sensor and remove it. Screw the new oxygen sensor into place.
3. Reconnect the wiring harness to the oxygen sensor and then close the hood. Turn the car on and allow it to warm up to normal operating temperature. Check to make sure the car is running smoothly and then take it for a test drive.