The oxygen sensor in a Volvo monitors the fuel being burned in the engine. It does this by measuring the exhaust gases in the exhaust piping. It then relays this information to the Volvo's ECU so that adjustments can be made if needed. The main purpose of the oxygen sensor or "O2 sensor" is to allow the vehicle to get the greatest gas mileage, most power and emit the lowest emissions possible. After roughly 100,000 miles, the O2 sensor may need to be replaced.
Place a small amount of anti-seize on the threads of the O2 sensor.
Unscrew the old O2 sensor, located in front of or behind the catalytic converter, depending on the year of the Volvo. Place the new O2 sensor into the threaded hole.
Tighten the O2 sensor until you feel resistance. Do not force the O2 sensor into place or damage may occur to the threads on either the O2 sensor itself or the hole in the piping.
Connect the electrical connector to the O2 bung.
Verify that the sensor is functioning properly by turning on the vehicle. Wait for the "check engine" light to come on, then wait for it to turn off. If the "check engine" light cycles properly and does not come back on again after it goes out, the O2 sensor is functioning properly.
