AutoCodes – Mercury – P0721 Mercury

P0721 Mercury Code - Output Shaft Speed Sensor Range/Performance

Quick Answer

The Output Shaft Speed (OSS) Sensor provides the Powertrain Control Module (PCM) with information about the rotational speed of an output shaft. Common causes include Faulty Output Speed Sensor (OSS), Output Speed Sensor harness is open or shorted, Output Speed Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0721 Mercury indicates Output Shaft Speed Sensor Range/Performance.
Common causes: Common causes include Faulty Output Speed Sensor (OSS), Output Speed Sensor harness is open or shorted, Output Speed Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 552

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 13, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0721 Mercury Description

The Output Shaft Speed (OSS) Sensor provides the Powertrain Control Module (PCM) with information about the rotational speed of an output shaft. The PCM uses the information to control and diagnose powertrain behavior. In some applications, the sensor is also used as the source of vehicle speed. The sensor may be physically located in different places on the vehicle, depending upon the specific application. The design of each speed sensor is unique and depends on which powertrain control feature uses the information that is generated. The Diagnostic Trouble Code (DTC) will set if the PCM detects an OSS sensor out of range circuit.

OBDII Code P0721 Mercury - Output Shaft Speed Sensor Range/Performance - AutoCodes.com — P0721 Mercury Code - Output Shaft Speed Sensor Range/Performance

What does this mean?

What are the Possible Causes of the DTC P0721 Mercury?

Faulty Output Speed Sensor (OSS)
Output Speed Sensor harness is open or shorted
Output Speed Sensor circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC P0721 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0721 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0721 Mercury code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0721 Mercury Code

1. What are the common symptoms of OBDII code P0721 in a Mercury vehicle?

- Common symptoms include issues with shifting gears, erratic speedometer readings, and the transmission going into limp mode.

2. What can cause the OBDII code P0721 to trigger in a Mercury vehicle?

- The code P0721 is typically triggered by a faulty output shaft speed sensor, damaged wiring or connectors related to the sensor, or internal transmission issues.

3. How can I diagnose the OBDII code P0721 in my Mercury?

- Diagnosing the code may involve checking the output shaft speed sensor for proper operation, inspecting the sensor's wiring for damage, and using a scan tool to analyze transmission data.

4. Can a faulty output shaft speed sensor be repaired, or does it need to be replaced in a Mercury vehicle?

- In most cases, a faulty output shaft speed sensor will need to be replaced rather than repaired to resolve the P0721 code and related transmission issues.

5. Are there any DIY tips for fixing the OBDII code P0721 in a Mercury?

- DIY tips for addressing the P0721 code may include checking and cleaning the sensor's connections, ensuring proper sensor alignment, and conducting a visual inspection of the sensor.

6. How critical is it to address the OBDII code P0721 promptly in a Mercury vehicle?

- It is important to address the P0721 code promptly to prevent further damage to the transmission and ensure the vehicle operates safely and efficiently.

7. Can the OBDII code P0721 be intermittent in a Mercury vehicle?

- Yes, the P0721 code can sometimes be intermittent, causing sporadic transmission issues and warning lights to appear.

8. Are there any recalls or technical service bulletins related to the OBDII code P0721 in Mercury vehicles?

- It is recommended to check with a Mercury dealership or online resources for any recalls or technical service bulletins related to the P0721 code in your specific vehicle model.

9. How much can I expect to pay for repairing the OBDII code P0721 in a Mercury vehicle?

- The cost of repairing the P0721 code can vary depending on the extent of the issue, but it may involve sensor replacement, wiring repairs, and labor costs, which can range from a few hundred to over a thousand dollars.

10. Will resetting the OBDII code P0721 in a Mercury vehicle make the issue go away permanently?

- Resetting the code may temporarily clear the warning light, but if the underlying issue with the output shaft speed sensor or transmission persists, the code is likely to reappear. It is essential to diagnose and address the root cause of the problem for a permanent fix.