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

An oxygen or O2 sensor steps oxygen levels in the exhaust stream and also the PCM provides this information to adjust and keep a appropriate air-to-fuel ratio. An O2 sensor is considered a component of the emissions manage system, together the air-fuel ratio plays a an essential road in carbon and also NOx emissions.

Applicable design Years: 1997 - 2003 Ford F-150 (general procedures applicable to newer 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 fails or generates an erratic/out-of-range signal, the PCM will certainly resort to using a predetermined, conservative estimate in location of the real time reading. This have the right to yield reduced performance, fuel economy, and also throttle response. When a sensor failure is detected, a diagnostic trouble code (DTC) and also check engine light are typically set identifying the faulty O2 sensor. While it"s perfectly acceptable to only replace the sensor(s) that have actually triggered a DTC (DTCs will vary, but generally decide the bank and also upstream/downstream position), we"ve always replaced the O2 sensors in sets to ensure the selection of readings is equal between sensors.

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

For each sensor, you"ll should 1) disconnect the electrical connector on the sensor pigtail, 2) remove the old sensor, 3) download the new connector utilizing a liberal amount of anti-seize link on the threads, and 4) reconnect the electric connector. The is not uncommon for the threads in a sensor bung to piece - details ~ above repairing the threads can be found below.

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• The photo at left gives you a basic idea the the place of the O2 sensors. Each O2 sensor has actually a 22 mm nut at its base, yet they will also accept a 7/8" tool. O2 sensor sockets are generally compatible through both 7/8" and also 22 mm sizes. The hex head at the base of the sensor is very easy to round off with an open end wrench or crowfoot. That is very advised the only O2 sensor sockets or a flare seed wrench/crowfoot is provided to remove and also install the sensors. To make matters worse, you have the right to expect the sensors come be exceptionally tight in their bungs. You might need to access a variety of devices in order come reach all the sensors - execute not intend to reach them all through a simple wrench.


• Disconnect the negative battery cable.

• referring to the image at left, there room a selection of 22 mm, 7/8" sockets and also tools available to remove O2 sensors in border spacers - a range of these tools were compelled to remove and also install the four sensors. Part sensor places have higher spacial constraints 보다 others.


Driver next front sensor - The former sensor on the driver next is reasonably simple to eliminate with a 22 mm flare nut wrench. It is accessed from in ~ the truck.


Driver side rear sensor - due to the fact that this truck is 4 wheel drive, the transfer instance limits accessibility to the behind catalytic converter, i beg your pardon is wherein the O2 sensor is located. Loosening the exhaust clamp situated behind the catalytic converter and unbolting the exhaust collector that connects the exhaust system to the exhaust manifold enabled us to reduced a 2-3 foot section of the exhaust mechanism that includes the two catalytic converters. This gave us just sufficient room to access the sensor, eliminate it with a 22 mm flare seed wrench, install the new sensor, and also slide the exhaust back into place. This may not be compelled for all applications, yet it do the task much easier in this case.


Passenger next front sensor - The passenger side front O2 sensor is located straight behind the exhaust collector wherein the exhaust manifold connects come the exhaust system. This truck has the sensor pointing upwards, but some trucks will have actually the sensor pointing inward. Removal of the inside fender (plastic liner within the prior fender) and also the infection dipstick tube may be required. We were able to eliminate this sensor through unfastening fifty percent of the inside fender and pulling it out of the way. This is generally the many time consuming sensor to remove as result of its location, for this reason be prepared to use all the tools in your arsenal.

Passenger side rear sensor - Accessing this sensor is comparable to accessing the driver next rear, yet without having to disconnect the exhaust system. Friend may pick to eliminate the catalytic converter warm shield, yet we did not have to.

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O2 Sensor Bung subject Repair

If the object of the O2 sensor bung end up being damaged and also the brand-new sensor will not thread right into place, you"ll have to chase the threads through a tap. The is reasonably common because that the object to come to be damaged after removing a stubborn sensor - these room subjected to thousands of heating and also cooling cycles end the food of their life and tend to come to be stuck.

The threads room M18 x 1.5 and a special tap is easily accessible that is designed to fit right into tight locations. One example is Lisle 12230 (see attach for details). A normal tap is daunting to use as it will not fit in most situations due come spacial limitations. The dedicated tool is much shorter and works through a socket/wrench rather of a conventional tap handle.

Chase the threads utilizing a liberal quantity of cutting fluid (or even motor oil) top top the cutting teeth of the tap. Be certain to clean the subject by typically backing the tap out a full turn for every 1 to 2 cutting rotations. Once the threads have actually been repaired, clean the area thoroughly and also wipe any type of oil indigenous the exhaust tubing v a rag and also a solvent (brake cleaner, carb cleaner, etc). is no affiliated through nor endorsed by Ford Motor company or any kind of manufacturer discussed herein, unless explicitly listed otherwise.