Understanding Code P0720: Output Speed Sensor Circuit Malfunction

A malfunction has been detected in the output speed sensor circuit. The output speed sensor measures the rotational speed of the transmission output shaft, providing data used by the TCM for shift control and by the ECM for vehicle speed calculation. When this sensor is not functioning correctly, it can lead to various issues with your vehicle's performance, including erratic shifting and incorrect speed readings. Understanding this code is important for maintaining your vehicle's reliability and performance. Common causes of a P0720 code include a failed output speed sensor, which is the most straightforward explanation. If the sensor itself is not working, it cannot provide the necessary data to the transmission control module (TCM) or the engine control module (ECM). Another potential issue could be a damaged tone ring or reluctor wheel that the sensor reads. These components are essential for the sensor to accurately measure speed. If they are worn or broken, the sensor may not function properly. Wiring issues can also lead to a P0720 code. Open, short, or high-resistance wiring in the sensor circuit can disrupt the signal being sent to the TCM and ECM. Corroded or loose sensor connectors can cause similar problems, as they may not provide a stable connection for the sensor to communicate with the vehicle's computer systems. Additionally, metal debris in the transmission fluid can affect the sensor signal, leading to inaccurate readings. Lastly, a faulty TCM output speed sensor input circuit can also trigger this code, as it may not interpret the sensor's data correctly. When faced with a P0720 code, there are several suggested actions to take. First, inspect the output speed sensor and its connector for any physical damage or signs of corrosion. A visual inspection can often reveal issues that may not require extensive troubleshooting. Next, check the sensor wiring harness for any damage, chafing, or shorts. This step is crucial as damaged wiring can lead to intermittent or complete sensor failure. It is also important to verify the transmission fluid level and condition. Contaminated fluid can significantly affect sensor operation and may lead to further complications if not addressed. Ensure that the fluid is at the proper level and appears clean. If the fluid is dirty or has metal particles, it may need to be changed. Finally, consider having the tone ring and sensor circuit evaluated by a qualified technician. They can perform more in-depth diagnostics to determine if the sensor itself is faulty or if there are other underlying issues contributing to the P0720 code. Addressing these problems promptly can help prevent more severe transmission issues down the line, ensuring your vehicle remains reliable and efficient on the road.

SCAN YOUR
CAR NOW

Get an accurate diagnosis using your exact vehicle data. Free to scan with any BLE OBD-II adapter.