P0720 Output Speed Sensor Circuit Malfunction
The OBD2 code P0720 indicates a malfunction in the output speed sensor circuit, which measures the rotational speed of the transmission output shaft
Definition
Common causes
- Faulty output speed sensor
- Damaged wiring or connectors
- Poor electrical connections
- Malfunctioning transmission control module (TCM)
- Issues with the vehicle's computer system
- Low transmission fluid levels
- Internal transmission problems
- Corroded or shorted circuits
Common misdiagnoses
- Transmission issues
- Vehicle speed sensor failure
- Engine control module (ECM) problems
- Wiring or connector issues
- Input speed sensor malfunction
- Torque converter problems
- Faulty transmission fluid level or condition
- ABS sensor issues
Troubleshooting steps
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1. Check for Additional Codes
Use an OBD-II scanner to check for any other trouble codes that may be present. Codes related to the transmission or other sensors can provide additional context
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2. Inspect the Output Speed Sensor
Locate the output speed sensor (usually found on the transmission)
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3. Check for physical damage, corrosion, or loose connections at the sensor and its wiring harness
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4. Test the Sensor
Use a multimeter to test the output speed sensor. Check for proper resistance and voltage output according to the manufacturer's specifications
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5. If the sensor is faulty, replace it
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6. Check Wiring and Connectors
Inspect the wiring and connectors leading to the output speed sensor for any signs of wear, fraying, or damage
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7. Ensure that all connections are secure and free of corrosion
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8. Inspect the Transmission Fluid
Check the transmission fluid level and condition. Low or dirty fluid can affect sensor performance
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9. If the fluid is low, top it off or change it if it appears dirty or burnt
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10. Test the Circuit
Use a multimeter to check for continuity in the wiring between the output speed sensor and the ECM/TCM
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11. Look for any shorts to ground or open circuits
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12. Check for Mechanical Issues
Inspect the transmission for any mechanical issues that could affect the output speed sensor's operation, such as a failing torque converter or internal transmission problems
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13. Clear Codes and Test Drive
After performing repairs or replacements, clear the trouble codes using the OBD-II scanner
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14. Take the vehicle for a test drive to see if the code reappears
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15. Seek Professional Help
If the issue persists after performing these steps, consider seeking help from a professional mechanic or technician who has experience with transmission diagnostics. By following these troubleshooting steps, you can systematically identify and resolve the issue related to the P0720 code