How to Change an Oxygen Sensor on a 1998 Ford F-150 4.6L

The 1997 model year not only brought about a risky body change for the F-150, but also ushered in an all-new package of engines. Gone were the outdated 4.9-liter in-line six-cylinder, the 5.0-liter V-8 and the 5.8-liter V-8 engines; taking their places were the 4.2-liter V-6, the 4.6-liter V-8 and the 5.4-liter V-8 engines, respectively. All three engines gave the new F-150 a significant horsepower increase over the previous model year. The 1998 F-150s 4.6-liter engine has four oxygen sensors monitoring the truck's exhaust, checking for a lean or rich condition, as well as checking for toxic gasses escaping the engine. Replacing these sensors is a straightforward task -- once you know where Ford installed them.

Instructions

Look just below the exhaust manifold on the side of the engine the passengers side, if you are working on bank one, sensor one, or the drivers side for bank two, sensor one and find the oxygen sensor. Trace the oxygen sensor's wire upward until you reach the respective sensor's wiring harness. Ford uses bank one and bank two as a way to identify each side of the engine and the exhaust pipe that corresponds to it. Bank one is the passenger's side of the engine and bank two is the driver's side of the engine. Both oxygen sensors numbered one monitor the exhaust as it exits the combustion chamber on their respective side of the engine and verify that the fuel is burning at an efficient rate.

Pry upward on the locking tab on the failed oxygen sensors wiring harness and hold it up with a flathead screwdriver. Unplug the F-150s harness from the oxygen sensors harness.

Raise the front of the truck with a floor jack and slide jack stands under the trucks frame rails. Lower the F-150 onto the jack stands.

Crawl under the front of the truck and find bank one, sensor one on the exhaust pipe just below the passengers side exhaust manifold and bank two, sensor one on the drivers side exhaust pipe, just below the exhaust manifold.

Remove the oxygen sensor from the exhaust pipe with a ratchet and oxygen sensor socket.

Thread a new oxygen sensor into the exhaust pipe, then torque it to between 27 and 34 foot-pounds, using a torque wrench and oxygen sensor socket.

Raise the truck from the jack stands with a floor jack and remove the jack stands. Lower the truck to the ground.

Route the oxygen sensors pigtail in a way that it does not contact the exhaust manifold, then plug it into the F-150s wiring harness.

Follow Step 3 in the section titled Banks One and Two Oxygen Sensor One.

Crawl under the center of the truck and find the two oxygen sensors screwed into the exhaust pipe behind each catalytic converter. The one on the drivers side is bank two, sensor 2 and the one on the passengers side is bank one, sensor two.

Trace the failed oxygen sensors pigtail upward until you come to where the oxygen sensors wiring harness connects to the F-150s harness.

Remove and install the oxygen sensor by following steps 2, and 4 through 7 in the section titled Banks One and Two Oxygen Sensor One.