P0721 – OBD-II DTC

OBD-II DTC P0721 – Output Speed Sensor Circuit Malfunction

DTC P0721 meaning

DTC P0721 refers to a malfunction in the Output Speed Sensor Circuit. This diagnostic trouble code indicates that the Engine Control Module (ECM) has detected an issue with the signal from the output speed sensor, which is responsible for monitoring the rotational speed of the transmission output shaft. This information is crucial for the ECM to manage transmission shifting and overall vehicle performance.

DTC P0721 symptoms

Common symptoms associated with DTC P0721 may include:

• Illuminated check engine light
• Erratic or harsh shifting of the transmission
• Decreased fuel efficiency
• Transmission slipping or failure to engage
• Vehicle speedometer malfunction

DTC P0721 causes

Several factors can lead to the triggering of DTC P0721, including:

• Faulty output speed sensor
• Wiring issues, such as damaged or corroded connectors
• Short circuits or open circuits in the sensor circuit
• Faulty Engine Control Module (ECM)
• Transmission fluid issues, such as low fluid levels or contamination

DTC P0721 seriousness

DTC P0721 can be considered serious as it affects the transmission’s ability to function properly. If left unaddressed, it may lead to further transmission damage, reduced vehicle performance, and potential safety hazards due to erratic shifting or loss of power. It is advisable to diagnose and repair the issue promptly.

How to diagnose DTC P0721

To diagnose DTC P0721, follow these steps:

1. Use an OBD-II scanner to confirm the presence of DTC P0721.
2. Inspect the output speed sensor and its wiring for any visible damage or corrosion.
3. Check the sensor’s resistance and voltage output according to manufacturer specifications.
4. Test the wiring harness for continuity and proper grounding.
5. Examine the transmission fluid level and condition.
6. Clear the code and take the vehicle for a test drive to see if the code reappears.

How to fix DTC P0721 step-by-step instructions

To fix DTC P0721, follow these steps:

1. Inspect and repair any damaged wiring or connectors related to the output speed sensor.
2. Replace the faulty output speed sensor if it does not meet specifications.
3. Ensure the transmission fluid is at the correct level and is clean replace if necessary.
4. Reconnect all components and clear the DTC using an OBD-II scanner.
5. Perform a test drive to verify that the issue has been resolved and the code does not return.

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