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

An oxygen or O2 sensor actions oxygen levels in the exhaust stream and the PCM offers this details to adjust and preserve a appropriate air-to-fuel ratio. One O2 sensor is taken into consideration a ingredient of the emissions regulate system, together the air-fuel proportion plays a vital road in carbon and 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 an O2 sensor stops working 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. As soon as a sensor failure is detected, a diagnostic trouble code (DTC) and also check engine light room typically set identifying the faulty O2 sensor. If it"s perfect acceptable to only replace the sensor(s) that have actually triggered a DTC (DTCs will vary, yet generally decide the bank and also upstream/downstream position), we"ve always replaced the O2 sensors in sets to ensure the range of readings is equal in between sensors.

There space (4) O2 sensors on a 1997 - 2003 Ford F-150; two before the an initial catalytic converters on each bank of the engine and two within each that the rear catalytic converters ~ above each financial institution of the engine (see map below). The O2 sensors closest come the engine are described as "upstream" sensors, when the rearmost are referred to as "downstream" sensors. There is a difference between upstream and downstream sensors, therefore mind the correct component number(s) for her vehicle.

For each sensor, you"ll should 1) disconnect the electric connector ~ above the sensor pigtail, 2) remove the old sensor, 3) install the brand-new connector making use of a liberal quantity 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 can be discovered below.

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• The photo at left gives you a basic idea the the location of the O2 sensors. Each O2 sensor has actually a 22 mm nut in ~ its base, yet they will likewise accept a 7/8" tool. O2 sensor sockets are typically compatible v both 7/8" and also 22 mm sizes. The hex head at the basic of the sensor is incredibly easy to ring off v an open end wrench or crowfoot. It is very advised that only O2 sensor sockets or a flare seed wrench/crowfoot is used to remove and also install the sensors. To do matters worse, you can expect the sensors come be incredibly tight in their bungs. You may need to access a variety of tools in order to reach every the sensors - perform not intend to reach them all through a straightforward wrench.


• Disconnect the an adverse battery cable.

• introduce to the picture at left, there room a selection of 22 mm, 7/8" sockets and also tools obtainable to remove O2 sensors in confined spacers - a range of these tools were required to remove and also install the four sensors. Some sensor locations have better spacial constraints than others.


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


Driver side rear sensor - because this truck is 4 wheel drive, the transfer situation limits access to the rear catalytic converter, i m sorry is where the O2 sensor is located. Loosening the exhaust clamp situated behind the catalytic converter and unbolting the exhaust collector the connects the exhaust mechanism to the exhaust manifold enabled us to reduced a 2-3 foot section of the exhaust system that contains the two catalytic converters. This offered us just enough room to accessibility the sensor, eliminate it v a 22 mm flare seed wrench, download the new sensor, and slide the exhaust earlier into place. This might not be required for every applications, yet it made the job much much easier in this case.


Passenger next front sensor - The passenger side front O2 sensor is located directly behind the exhaust collector wherein the exhaust manifold connects come the exhaust system. This truck has actually the sensor pointing upwards, but some trucks will have the sensor pointing inward. Remove of the within fender (plastic liner inside the front fender) and the infection dipstick tube may be required. Us were able to eliminate this sensor by unfastening half of the within fender and also pulling it the end of the way. This is typically the most time spend sensor come remove as result of its location, therefore be ready to use all the tools in your arsenal.

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

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O2 Sensor Bung subject Repair

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

The threads room M18 x 1.5 and a distinct tap is easily accessible that is designed come fit into tight locations. One instance is Lisle 12230 (see link for details). A common tap is an overwhelming to use as it will not right in most situations due to spacial limitations. The committed tool is much shorter and works with a socket/wrench rather of a typical tap handle.

Chase the threads making use of a liberal quantity of cutting liquid (or even motor oil) ~ above the cutting this of the tap. Be sure to clean the subject by generally backing the tap out a full turn because that every 1 to 2 cutting rotations. When the threads have been repaired, clean the area thoroughly and wipe any oil from the exhaust tubing v a rag and also a solvent (brake cleaner, carbohydrate cleaner, etc). is not affiliated through nor endorsed through Ford Motor agency or any type of manufacturer discussed herein, unless explicitly listed otherwise.