Engine-CodesGeneric – P0721

P0721 Code - Output Shaft Speed Sensor Range/Performance

Quick Answer

The P0721 diagnostic trouble code indicates that the vehicle's engine control module (ECM) has detected a range/performance issue with the output shaft speed sensor. Common causes include Faulty output shaft speed sensor, Damaged wiring or connectors related to the sensor, Corrosion or debris affecting sensor operation. 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 indicates Output Shaft Speed Sensor Range/Performance.
Common causes
Common causes include Faulty output shaft speed sensor, Damaged wiring or connectors related to the sensor, Corrosion or debris affecting sensor operation.
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.
Table of contents Created and updated by William Orellana on Sep 12, 2024
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Code P0721 Description

The P0721 diagnostic trouble code indicates that the vehicle's engine control module (ECM) has detected a range/performance issue with the output shaft speed sensor. The output shaft speed sensor is a crucial component in the vehicle's transmission system, responsible for monitoring the rotational speed of the transmission output shaft. This information is essential for the ECM to accurately control the shifting of gears and ensure smooth operation of the transmission.

OBDII Code P0721 - Output Shaft Speed Sensor Range/Performance
P0721 Code - Output Shaft Speed Sensor Range/Performance

Common Causes of P0721

  1. Faulty output shaft speed sensor
  2. Damaged wiring or connectors related to the sensor
  3. Corrosion or debris affecting sensor operation
  4. ECM software or hardware issues
  5. Transmission fluid contamination affecting sensor performance

Symptoms of P0721

  1. Harsh or delayed shifting
  2. Erratic speedometer readings
  3. Transmission slipping
  4. Limp mode activation
  5. Check Engine Light illuminated

How to Fix P0721

  1. Diagnosis: The first step is to use a scan tool to retrieve the specific trouble code and perform a thorough inspection of the output shaft speed sensor and related components.
  2. Sensor Replacement: If the sensor is found to be faulty, it will need to be replaced with a new one. This may involve accessing the sensor located on the transmission housing and disconnecting the wiring harness.
  3. Wiring Inspection: Check the wiring harness and connectors for any damage, corrosion, or loose connections. Repair or replace any damaged components as needed.
  4. Clearing Codes: After replacing the sensor and addressing any wiring issues, the ECM codes should be cleared using a scan tool to reset the system and verify proper operation.
  5. Test Drive: Test drive the vehicle to ensure that the output shaft speed sensor is functioning correctly and that the transmission is shifting smoothly.

Cost to Fix P0721

The cost of repairing the output shaft speed sensor range/performance issue can vary depending on the make and model of the vehicle, as well as the labor rates at the auto repair shop. On average, the cost of replacing the output shaft speed sensor ranges from $150 to $300, including parts and labor. Additional costs may apply if there are wiring issues or other related components that need attention. It's important to consult with a qualified mechanic for a precise estimate based on the specific circumstances of your vehicle.

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Code P0721 Information for Specific Makes

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.

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