P0725 OBD-II: Engine Speed Input Circuit

What Does P0725 Code Mean?

OBD-II Code P0725 is defined as a Engine Speed Input Circuit Malfunction

The purpose of the automatic transmission is to match the engine's optimum power and torque characteristics to the driver's desired rate of acceleration and speed by auto-selecting different gear ratios or 'speeds' to power the wheels. When the code P0725 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM is not seeing a reliable or rational speed signal from the Transmission's Input/Turbine Sensor.

P0725 Symptoms

• Check Engine Light will illuminate
• Vehicle will not shift properly
• Decrease in fuel economy
• In unusual cases, there are no adverse conditions noticed by the driver
• In some cases, there may be performance problems, such as uneven shifting or slipping between gears.

Common Problems That Trigger the P0725 Code

• Defective Input/Turbine Speed Sensor
• Defective Input/Turbine Speed Sensor Wiring or Connection
• Defective Shift Solenoids
• Defective Engine Coolant Temperature Sensor
• Defective Valve Body
• Dirty transmission fluid that restricts the hydraulic passages

Common Misdiagnoses

• Engine Misfire problem
• Internal Transmission problem
• Driveline problem

Polluting Gases Expelled

• HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog
• CO (Carbon Monoxide): Partially burned fuel that is an odorless and deadly poisonous gas
• NOX (Oxides of Nitrogen): One of the two ingredients that, when exposed to sunlight, cause smog

P0725 Diagnostic Theory for Shops and Technicians

There may be greater than a specified RPM difference between the rotational speed of the Input RPM Sensor and the Transmission Output RPM Sensor. This can occur during shifting or when driving at steady speeds in the same gear. It often implies that the transmission is slipping.

When diagnosing a P0725 code, it is important to record the freeze frame information and then to duplicate the code setting conditions with a test drive. Pay close attention to the engine load, throttle position, RPM, and road speed because a P0725 can be difficult to detect.