What does it mean?
P1725 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: NT Revolution Sensor Circuit Malfunction (Input Turbine Speed Sensor) .
Symptoms
- MIL (check engine lamp) on with a transmission warning indication
- Flared, delayed or very harsh shifts because the module loses slip control
- Torque converter lockup never applies, so cruise RPM stays high
- Limp mode with a single fixed gear after repeated faults
- Turbine RPM reads zero or jumps erratically on scan tool live data
Likely causes
- Failed turbine speed sensor or a pickup face loaded with metallic debris
- Corrosion, ATF wicking or bent pins in the sensor connector
- Open, shorted or high resistance signal, ground or supply wire in the harness
- Excessive air gap, loose sensor mounting or a damaged reluctor ring tooth
- Clutch or gear wear releasing swarf that disturbs the magnetic pickup
- Low or badly degraded ATF causing unstable turbine speed readings
- Faulty module input circuit, only after all wiring checks pass
How to fix it
- Compare engine RPM, turbine RPM and output speed side by side on live data during a road test
- Unplug the sensor and inspect for ATF, corrosion, bent or pushed-out terminals
- Measure sensor resistance or view its output waveform with a meter or oscilloscope
- Wiggle the harness and connector while watching live data for dropouts
- Check the signal, ground and reference circuits for opens and shorts against the wiring diagram
- Remove the sensor and inspect the tip for metal fuzz, which points to internal wear
- Replace the sensor after verification, and investigate the transmission internals if debris was found