P0725 - ENGINE SPEED INPUT CIRCUIT MALFUNCTION

Diagnostic code P0725 indicates that the PCM (Powertrain Control Module) has detected a fault in the VSS (Vehicle Speed Sensor) input signal circuit, this may be due to an electrical or mechanical problem.

The Vehicle Speed Sensor (VSS) is usually located in the gearbox, it is close to the front of the input shaft. Its position makes it work as a seal with the transmission box because this sensor has an electromagnetic hall effect, it is positioned to allow a toothed ring to pass close to its magnetic tip, which is attached to the input shaft of the transmission so that when the shaft is rotated, the two are rotated together. The raised areas of the teeth function as an electromagnetic complement to the motor speed input circuit, while the lowered areas between the teeth suspend the circuit.

These fast suspensions create an electromagnetic waveform pattern that represents a particular frequency and degree of voltage, this is defined by the Powertrain Control Module (PCM) as the input speed of the motor. If the PCM does not recognize the appropriate motor speed input signal for a certain period and under certain circumstances, the DTC code P0725 is established.

• The check engine light is on.
• The speedometer is working erratically.
• In automatic transmissions, it can be abrupt when making changes.
• The transmission is slipping.

The DTC code P0725 may present the following problems:

• The magnetic tip of the VSS sensor may contain a lot of metal residues.
• The Vehicle Speed Sensor (VSS) wires or their respective connectors may be shorted.
• The VSS (Vehicle Speed Sensor) may be defective.
• The Vehicle Speed Sensor (VSS) slip ring may be worn or damaged.

To solve the code P0725, you can do the following:

• When there are codes related to the automatic transmission, the first thing to do is to check the transmission fluid, both its level and its state. If you notice that the level is low, check the transmission and lines for leaks. If there is a leak in the transmission, it will be necessary to remove the transmission and make the corresponding repair. Likewise, if you notice that it smells of burning or has a black color, it is an indication that may be producing the failure. You can change the liquid.
• Visually, inspect the cables and their respective connectors for damage caused by corrosion or friction that wears them out.
• Using a digital multimeter, check the VSS (Vehicle Speed Sensor) and compares the results with the vehicle specifications, as well as checking the magnetic tip of the sensor, as it may have metal residue.
• If there are no problems with the wiring or the fluid, with a scanner look at the engine speed input signal, if it varies from the engine RPM the Vehicle Speed Sensor (VSS) may be defective. There is also the possibility of a worn or faulty slip ring. Change it if necessary.