How to Change the Oxygen Sensors on a Ford Expedition

by Dan Ferrell
Photo courtesy of IFCAR at Wikipedia.org.

The oxygen sensors gather and send information to the Engine Management System (EMS) on your Ford Expedition. The EMS uses this information to regulate the air-fuel mixture and control vehicle emissions. If the sensor or sensors have failed, it is necessary to change them.

Step 1

Park the Expedition in a safe and level surface. Set the transmission to the neutral position.

Step 2

Open the hood, lift the front of the vehicle using a floor jack and safely support it on jack stands.

Step 3

Starting at the exhaust manifold at either side of the engine, follow the exhaust pipe down. Right before the pipe connects to the catalytic converter, you will see the first heated oxygen sensor threaded on to the exhaust pipe. And right after the catalytic converter, you will find the other sensor. Both exhaust pipes are configured the same way; depending on your engine model, you might have two or four of these sensors installed. Whatever sensor or sensors you need to replace, follow this same procedure.

Step 4

Unplug the electrical connector of the oxygen sensor you need to change. Do not pull the wires to unplug the sensor, always grab the plastic connector.

Step 5

Remove the sensor using a ratchet and an oxygen sensor socket.

Step 6

Compare the old sensor with the new one and make sure they match up.

Step 7

Apply a light coat of anti-seize compound to the threads of the new sensor and install it by hand first.

Step 8

Tighten the sensor using the ratchet and sensor socket, but do not over tighten or the sensor and threads may be damaged.

Plug the oxygen sensor electrical connector. If you need to replace any one of the other sensors, follow steps 4 through 8; then lower the vehicle.

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