How to replace the O2 Sensors in a 1997 - 2003 F-150

An oxygen or O2 sensor procedures oxygen level in the exhaust stream and also the PCM uses this info to adjust and maintain a proper air-to-fuel ratio. An O2 sensor is taken into consideration a ingredient of the emissions regulate system, together the air-fuel proportion plays a critical road in carbon and NOx emissions.

Applicable design Years: 1997 - 2003 Ford F-150 (general measures applicable to more recent models) 1997 - 2003 downstream O2 sensor (rear): Motorcraft DY1093 (Ford F85Z-9G444-BA) 1997 - 1998 upstream O2 sensor (front): Motorcraft DY832 (Ford F88F-9F472-AB) 1999 upstream O2 sensor (front): Motorcraft DY1093 (Ford F85Z-9G444-BA) 2000 - 2003 upstream O2 sensor (front): Motorcraft DY835 (Ford XL3F-9F472-AA)

When one O2 sensor stops working or generates an erratic/out-of-range signal, the PCM will resort to using a predetermined, conservative calculation in ar of the actual time reading. This have the right to yield reduced performance, fuel economy, and also throttle response. Once a sensor fail is detected, a diagnostic trouble code (DTC) and also check engine light are typically collection identifying the faulty O2 sensor. If it"s perfect acceptable to just replace the sensor(s) that have triggered a DTC (DTCs will certainly vary, however generally accurately decide the bank and upstream/downstream position), we"ve constantly replaced the O2 sensors in sets to ensure the variety of readings is equal in between sensors.

There space (4) O2 sensors on a 1997 - 2003 Ford F-150; two prior to the first catalytic converters ~ above each bank of the engine and also two inside each of the rear catalytic converters top top each bank of the engine (see map below). The O2 sensors closest to the engine are described as "upstream" sensors, if the rearmost are referred to as "downstream" sensors. There is a difference between upstream and also downstream sensors, therefore mind the correct part number(s) for your vehicle.

For each sensor, you"ll have to 1) disconnect the electric connector on the sensor pigtail, 2) remove the old sensor, 3) download the new connector making use of a liberal lot of anti-seize compound on the threads, and also 4) reconnect the electric connector. The is not unusual for the subject in a sensor bung to piece - details top top repairing the threads have the right to be uncovered below.

You are watching: Ford f150 4.2 o2 sensor location

Click any type of thumbnail to see high resolution fullsize photo w/ enhancement details (where applicable)


• The picture at left offers you a general idea the the location of the O2 sensors. Each O2 sensor has actually a 22 mm nut at its base, however they will also accept a 7/8" tool. O2 sensor sockets are frequently compatible through both 7/8" and 22 mm sizes. The hex head at the basic of the sensor is extremely easy to ring off through an open end wrench or crowfoot. It is highly advised that only O2 sensor sockets or a flare seed wrench/crowfoot is provided to remove and also install the sensors. To do matters worse, you have the right to expect the sensors to be incredibly tight in their bungs. You might need to accessibility a selection of tools in order to reach all the sensors - execute not suppose to with them all with a an easy wrench.


• Disconnect the an adverse battery cable.

• referring to the image at left, there are a range of 22 mm, 7/8" sockets and also tools obtainable to remove O2 sensors in limit spacers - a range of these tools were required to remove and also install the four sensors. Part sensor areas have greater spacial constraints than others.


Driver side front sensor - The prior sensor top top the driver side is relatively simple to eliminate with a 22 mm flare nut wrench. That is accessed from beneath the truck.


Driver side behind sensor - because this truck is 4 wheel drive, the transfer situation limits access to the behind catalytic converter, i beg your pardon is wherein the O2 sensor is located. Loosening the exhaust clamp located behind the catalytic converter and unbolting the exhaust collector that connects the exhaust system to the exhaust manifold enabled us to lower a 2-3 foot section of the exhaust system that consists of the two catalytic converters. This offered us just enough room to access the sensor, eliminate it with a 22 mm flare seed wrench, install the brand-new sensor, and slide the exhaust earlier into place. This may not be required for all applications, but it made the task much much easier in this case.


Passenger side front sensor - The passenger next front O2 sensor is located straight behind the exhaust collector where the exhaust manifold connects to the exhaust system. This truck has actually the sensor pointing upwards, however some van will have the sensor pointing inward. Remove of the inner fender (plastic liner within the front fender) and the infection dipstick tube may be required. We were maybe to remove this sensor by unfastening fifty percent of the inner fender and pulling it the end of the way. This is usually the most time consuming sensor come remove due to its location, therefore be prepared to use all the tools in her arsenal.

Passenger side rear sensor - Accessing this sensor is comparable to accessing the driver side rear, however without having actually to disconnect the exhaust system. Friend may pick to remove the catalytic converter heat shield, yet we walk not have to.

See more: Painting Semi Gloss Over Semi Gloss Paint, Painting Over Semi

O2 Sensor Bung subject Repair

If the subject of the O2 sensor bung end up being damaged and also the new sensor will certainly not thread into place, you"ll should chase the threads through a tap. The is fairly common because that the threads to end up being damaged after removing a stubborn sensor - these room subjected to hundreds of heating and also cooling cycles end the course of their life and tend to come to be stuck.

The threads space M18 x 1.5 and also a one-of-a-kind tap is accessible that is designed come fit right into tight locations. One example is Lisle 12230 (see attach for details). A common tap is daunting to use as it will not fit in most instances due to spacial limitations. The specialized tool is much much shorter and works with a socket/wrench instead of a conventional tap handle.

Chase the threads making use of a liberal quantity of cutting fluid (or even motor oil) ~ above the cutting this of the tap. Be sure to clean the object by typically backing the tap the end a full turn for every 1 to 2 cutting rotations. When the threads have actually been repaired, clean the area thoroughly and wipe any oil from the exhaust tubing v a rag and a solvent (brake cleaner, carbohydrate cleaner, etc). is not affiliated through nor endorsed by Ford Motor company or any kind of manufacturer discussed herein, unless explicitly noted otherwise.