2018-2024 Ford Expedition Transmission Output Shaft Speed Sensor Replacement Guide
Experiencing erratic shifting or a dead speedometer? Your transmission output speed sensor could be the problem.
- Before replacing the sensor for shifting issues, confirm a P0720, P0721, or P0722 code is present, as other internal 10R80 transmission problems cause similar symptoms.
- Symptoms of a bad OSS are specific: erratic shifting, a faulty speedometer, and cruise control failure.
- A quality aftermarket sensor from a brand like Standard Ignition offers significant cost savings over the OEM part for this repair.
- Replacement is a simple, DIY-friendly job that requires removing a single bolt and an electrical connector.
Is a Bad Speed Sensor Causing Your Transmission Problems?
Important Note for 10R80 Transmission Owners
The 2018-2024 Ford Expedition uses the 10R80 10-speed automatic transmission, which is known for having issues with harsh, jerky, or delayed shifting. Ford has released multiple Technical Service Bulletins (TSBs) for these problems, which are often caused by internal components like the valve body or CDF clutch drum, or by software that needs updating. While a bad output speed sensor can cause shifting problems, it is crucial to verify the specific Diagnostic Trouble Code (DTC) before replacing this part. If your check engine light is on, scan the vehicle. A code P0720, P0721, or P0722 specifically points to the output speed sensor circuit. If you have other transmission codes, the sensor is likely not the cause of your issue.
Symptoms of a Failing Output Speed Sensor
When the OSS fails, it gives clear signs. The most common issue is a check engine light with code P0720. You may also experience harsh or unpredictable shifting because the computer doesn't know when to change gears. Another obvious symptom is an erratic or completely dead speedometer, since the OSS provides the data for it. Finally, you will likely find that your cruise control no longer works, as it relies on a steady speed signal from this sensor to function.
Choosing the Right Aftermarket Sensor
For a part like the output speed sensor, you have a choice between the original equipment manufacturer (OEM) part from Ford (Motorcraft) and aftermarket options. Aftermarket brands like Standard Ignition (also known as SMP) are established manufacturers that produce reliable, direct-fit replacement parts. They are designed to match the original's performance and often undergo extensive testing. Given that the OEM sensor can cost nearly twice as much as a quality aftermarket alternative, choosing an aftermarket brand is a smart way to save money on this repair without sacrificing reliability.
| Part/Service | Estimated Cost |
|---|---|
| New OEM (Motorcraft) Part | $48 - $77 |
| New Aftermarket (Standard Ignition) Part | $25 - $36 |
| Shop Labor | $60 - $120 |
Frequently Asked Questions (FAQ)
Where is the output speed sensor located on a 2018-2024 Expedition?
The output shaft speed sensor (OSS) is located on the exterior of the transmission. On many models, you can find it on the driver's side of the transmission case, toward the rear. On 4WD models, the sensor that measures final vehicle speed is located on the transfer case near the rear driveshaft. It is typically held in by a single 8mm or 10mm bolt and has an electrical connector attached.
Can I replace this sensor myself?
Yes, this is a very DIY-friendly repair. The job requires basic hand tools, and since the sensor is on the outside of the transmission, no special procedures are needed. You simply disconnect the electrical plug, remove one bolt, pull the old sensor out, and install the new one. A small amount of transmission fluid may leak out, so it's good to have the new sensor ready to install quickly.
What's the difference between an input and output speed sensor?
The transmission has at least two main speed sensors. The Input Speed Sensor (ISS) measures the speed of the transmission's input shaft (how fast it's being spun by the engine). The Output Speed Sensor (OSS) measures the speed of the output shaft (how fast power is being sent to the wheels). The computer compares these two signals to verify the transmission is in the correct gear and to detect any slipping. The 10R80 transmission actually has four speed sensors in total for more precise control.
Do I need to perform a transmission relearn procedure after replacing the sensor?
Generally, no. Replacing the sensor should restore the proper signal, and the computer will begin using the new data immediately. However, the 10R80 transmission does use an adaptive learning strategy that adjusts shift points over time. If you have been driving with a faulty sensor for a while, the transmission may have learned some bad habits. It may take a few days of normal driving for the shifts to feel perfectly smooth again.
Technical Specifications
OEM Part Numbers: L1MZ-7H103-A HL3Z-7H103-B HL3Z-7H103-A DY-1375
2-terminal Hall-effect sensor used for measuring transmission output shaft rotational speed.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Ford Expedition: