P0720 - Output Speed Sensor Circuit Malfunction

Introduction

The DTC P0720 trouble code is a common problem that can occur in vehicles equipped with automatic transmissions. This code indicates a malfunction in the output speed sensor circuit, a crucial component for the proper functioning of the transmission. Diagnosing and fixing this problem requires a thorough understanding of both the components involved and self-diagnostic techniques. In this article, we will explore the symptoms, causes, diagnosis, and troubleshooting of the DTC P0720 problem.

Symptoms

Symptoms associated with the P0720 trouble code may vary depending on the vehicle, but in general may include:

  • Irregular gear shifting :
    The vehicle may have difficulty shifting gears, with jerky shifts or delays in shifting.

  • Transmission slippage :
    You may feel some transmission slippage, especially during acceleration.

  • Warning light :
    The Check Engine Light comes on on the dashboard.

  • Reduced performance :
    The vehicle may lose power or become unresponsive.

  • Related DTC Codes :
    Other DTC codes may also appear, such as P0721 (Output speed sensor circuit - low signal) or P0722 (Output speed sensor circuit - high signal).

Cause

The causes of the DTC code P0720 can be many and include:

  • Output speed sensor failure :
    The sensor itself may be faulty, causing incorrect readings.

  • Wiring problems :
    Damaged wires, loose or corroded connectors can interrupt the signal from the sensor to the ECU.

  • ECU fault :
    Although less common, a faulty engine control unit can cause problems receiving or processing the sensor signal.

  • Mechanical problems :
    Transmission defects, such as worn gears or torque converter malfunctions, can affect sensor readings.

Diagnosis

Diagnosing the problem can be done by following some basic steps:

  1. DTC Code Scan :
    Use an OBD-II scanner to identify the P0720 trouble code and any other related codes.

  2. Visual inspection :
    Inspect the output speed sensor wiring and connectors for any signs of wear, damage, or corrosion.

  3. Sensor Test :
    Measure the resistance of the output speed sensor with a multimeter. Specifications may vary, but an abnormal value indicates a faulty sensor.

  4. Voltage control :
    Verify that the sensor is receiving proper power and that the output signal complies with the manufacturer's specifications.

  5. ECU Test :
    If all other components are in working order, test the engine control unit for any faults or malfunctions.

Resolution and repair

Once you have identified the cause of the problem, you can proceed with the resolution and repair:

  • Sensor Replacement :
    If the output speed sensor is faulty, replacing it is often the simplest and most effective solution.

  • Wiring Repair :
    If any cables or connectors are damaged, repair or replace the damaged components.

  • Replacing the ECU :
    If the engine control unit is confirmed as faulty, it will require replacement or reprogramming.

  • Transmission check :
    If mechanical problems are present, a thorough check of the transmission is essential.

Insight into the components involved

Output Speed Sensor

The output speed sensor is an electrical component that measures the rotational speed of the transmission output shaft. It is usually a Hall effect sensor or a magnetic type sensor. Its readings are critical to the proper functioning of the automatic transmission, as the ECU uses this information to determine the best time to change gear.

Wiring and Connectors

The wiring that connects the speed sensor to the ECU is equally important. Any break in the circuit, due to wear or damage, can lead to incorrect or no readings. It is essential to use high quality connectors and ensure they are well soldered to avoid contact problems.

Conclusions

DTC P0720 indicates a malfunction in the output speed sensor circuit and can significantly affect the performance of the vehicle. Accurate diagnosis, followed by timely resolution of the problem, is essential to ensure optimal operation of the transmission. Knowing the symptoms, causes, and diagnosis and repair techniques can help auto repairers resolve this problem effectively, improving customer satisfaction and the reputation of their service.

Important
Not all OBD2 codes used by one manufacturer are used by other brands, and may not have the same meaning.
The information presented here is for informational purposes only. We are not responsible for any actions you take on your vehicle. If you have any concerns about repairing your vehicle, please contact your repair shop.