How to Change Oxygen Sensors on 1998 BMW 328I

The oxygen sensor, or O2 sensor, on the 1998 BMW 328i is a critical part of the engine management system. Reading the percent of oxygen in the exhaust gases, the sensor converts the percentage to milliamps and sends it to the engine computer. From that number, the computer can determine if the engine is rich and lean and it will adjust the pulse width or air/fuel mix at the fuel injector. The sensor sits in the exhaust system just below the exhaust manifold.

Things You'll Need

• Jack
• Jack stands
• Oxygen sensor socket
• Ratchet

Instructions

1. Raise the front of your 328i off the ground with a jack. Support the car by placing a set of jack stands under the front suspension of the car and lower the car onto them.

2. Locate the oxygen sensor in the exhaust pipe just below the exhaust manifold. Release the locking tab on the wiring harness connector and separate the sensor side of the connector from the side of the car. Install a oxygen sensor socket over the oxygen sensor and rotate it counterclockwise with a ratchet.

3. Remove the sensor from the exhaust pipe and discard it. Install the new sensor into the threaded hole in the pipe then tighten it with the oxygen sensor socket and ratchet. Route the wiring harness from the new sensor to the wiring harness connector on the car and connect the two connector halves, pushing them together until the locking tab engages.

4. Raise the car off the jack stands with a jack. Remove the jack stands from under the car and carefully lower it back to its wheels. Remove the jack from under the car.

References

• “Haynes Repair Manuals 1992 to 1998 3-series”; John H Haynes, 1998