AutoCodes – Acura – P0721 Acura

P0721 Acura Code - Output Shaft Speed Sensor Range/Performance

Quick Answer

The Output Shaft (Countershaft) Speed Sensor is attached to the transmission housing to sense countershaft revolutions. Common causes include Faulty Output Shaft (Countershaft) Speed Sensor, Output Shaft Speed Sensor harness is open or shorted, Output Shaft 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 Acura indicates Output Shaft Speed Sensor Range/Performance.
Common causes: Common causes include Faulty Output Shaft (Countershaft) Speed Sensor, Output Shaft Speed Sensor harness is open or shorted, Output Shaft 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 11,065

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
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0721 Acura Description

The Output Shaft (Countershaft) Speed Sensor is attached to the transmission housing to sense countershaft revolutions. The Engine Control Module (ECM) determines the vehicle speed according to the signal from the Output Shaft (Countershaft) Speed Sensor to the control units. If no signal from the Output Shaft (Countershaft) Speed Sensor is received for a set period of time, the ECM detects a malfunction, and a Diagnostic Trouble Code (DTC) is stored.

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

What does this mean?

What are the Possible Causes of the DTC P0721 Acura?

Faulty Output Shaft (Countershaft) Speed Sensor
Output Shaft Speed Sensor harness is open or shorted
Output Shaft Speed Sensor circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0721 Acura?

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 does this mean?

Code Tech Notes

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0721 Acura 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.

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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 Acura Code

What does the OBDII code P0721 mean for an Acura?

P0721 indicates a problem with the output shaft speed sensor, specifically that its signal is out of the expected range or performance parameters.

What are the symptoms of code P0721 in an Acura?

Symptoms may include erratic shifting, failure to shift gears, reduced fuel efficiency, and the vehicle going into limp mode.

What causes the P0721 code to appear in an Acura?

Common causes include a faulty output shaft speed sensor, damaged wiring or connectors, a malfunctioning transmission control module (TCM), or internal transmission issues.

Can I drive my Acura with the P0721 code?

Driving with this code is not recommended as it can lead to transmission damage, erratic shifting, and unsafe driving conditions.

How do I diagnose the P0721 code in an Acura?

Diagnosis involves scanning for codes, inspecting the output shaft speed sensor and its wiring, checking the TCM, and possibly performing transmission tests.

How do I fix the P0721 code in an Acura?

Repairs may include replacing the output shaft speed sensor, repairing damaged wiring, updating or replacing the TCM, or addressing internal transmission issues.

What tools are needed to fix the P0721 code?

You may need an OBDII scanner, multimeter, basic hand tools, and potentially specialty tools for transmission work.

Is the output shaft speed sensor expensive to replace in an Acura?

The cost of replacing the sensor typically ranges from $100-$300, including parts and labor, depending on your location and model.

Can a dirty transmission fluid cause the P0721 code?

Yes, contaminated or low transmission fluid can interfere with sensor readings and contribute to this code.

How can I prevent the P0721 code from occurring on my Acura?

Regular maintenance, such as keeping transmission fluid clean and at proper levels, inspecting wiring, and addressing sensor issues early, can help prevent this code.