- Check Engine Light is ON
- A decrease in fuel economy
- Engine Hesitation or misfire
- Rough Idling
What you will need
- Park the BMW 3-Series and open the hood.
- Disconnect the negative battery terminal. The battery is located in the trunk of your car. Remove the trim on the passenger side of the trunk, and you will be able to locate the battery negative terminal.
- Locate the oxygen sensor on your BMW 3-Series. In this picture, you can see the upstream oxygen sensor. This o2 sensor can be easily accessed by standing next to the front passenger fender. If you need to replace the downstream (Bank 1 Sensor 2), you will have to jack up the car and access the sensor from underneath.
- Disconnect the O2 sensor. Press the connector and pull it away to unplug the oxygen sensor wire harness. The wire harness is secured to the engine block, as shown in this picture.
- Remove O2 Sensor. Replace the oxygen sensor socket on the sensor and break it loose. Remove the old BMW 3-Series oxygen sensor.
- Install a new O2 sensor. Watch a video on how to replace the oxygen sensor. Install the new oxygen sensor and remember to torque the new BMW oxygen sensor to spec.
- Connect wire harness. Connect the oxygen sensor wire harness by plugging it in.
This guide applies to 3-Series such as 316i, 318i, 320i, 323i, 325i, 328i, 330i, 335i, 325d, 330d, and M3. Applicable chassis include the E90, E91, E92, and E93.