Cost: $80

Difficulty:

The Bmw Oxygen sensor measures the amount of oxygen in the exhaust after combustion and signals the computer to adjust the air/fuel mixture.

Poor performance, poor fuel economy and high emissions are the failure syndromes.

Check this great O2 sensor FAQ.

• 02 sensor socket (can be purchased at Autozone)
• Lot's of WD 40
• Rachet, extensions and u-joints
• Anti seize compound

Place the front of the car on jacks or use a ramp, then spray the old sensor with a lot of WD40 (with cold exhaust). Let it sit for awhile then you can remove the sensor with the sensor socket some extensions and u-joints. Don't forget to apply a coat of anti-seize compound on the new sensor threads. NOT on the tip!!!

In any model, you don't have to remove any part of the exhaust line.

M20 : The O2 sensor is located below the #6 cylinder on the front of the exhaust pipe. The connector is located on the right-hand rear of the engine, near the electronics box.

M50 : The O2 sensor is located at the front of the catalytic converter. The connector is located on the left-hand side of the engine, below the starter.

The M60 engine uses two O2 sensors located at the front of the catalytic converters.

The connector is located beneath the car under the transmission.

The 535i uses a single O2 sensor located at the front of the catalytic converter under the car. The connector is located at the rear of the engine compartment, lower left-hand side.