P1901 - FAULT CODE - OBD2

P1901 Code failures by brands

P1901 FORD, LINCOLN, MERCURY: TURBINE SHAFT SPEED SENSOR INTERMITTENT CIRCUIT.

P1901 MAZDA: TURBINE SHAFT SPEED SENSOR INTERMITTENT.

Description of DTC code P1901

On vehicles using automatic transmissions, engine power is sent to the transmission through the Torque Converter Clutch (TCC). This converter consists of two parts that constantly contact each other. One half is connected to the engine and the other half is driven by the transmission fluid, which is sent to the converter by the rotational movement of the half that is connected to the engine.

Typically, vehicles have two turbine speed sensors. On one side, one sensor monitors the rotational speed of the drive side of the TCC, while the other sensor, referenced by code P1901, specifically checks the rotational speed of the turbine output shaft. The PCM (Powertrain Control Module) compares both signals in order to calculate the amount of slip of the various transmission components and the slip of the Torque Converter Clutch.

The P1901 OBDII fault code is manufacturer specific and refers specifically to the sensor and circuitry that is responsible for monitoring the rotational speed of the transmission turbine shaft. This code is set when the signal provided by this sensor to the PCM becomes irregular or suffers interruptions. It is important to note that this shaft should not be confused with the transmission output shaft.

Symptoms of fault code P1901

Check Engine lamp illuminated.
Difficulties when shifting gears.
Cruise control is not available on some vehicles.
Malfunctioning speedometer.
The vehicle goes into fault test mode.

Causes of OBD2 P1901

The reasons for storing the DTC P1901 OBD2 code are:

The electrical circuit could have damage to the wiring or connectors.
The Turbine Speed Sensor could be in bad condition.
Possibly the reluctor ring could be in poor condition.

Possible solutions of the DTC code P1901

The steps to follow for troubleshooting the P1901 OBDII diagnostic code are as follows:

As a first step consult the TSB (Technical Service Bulletins). It is also necessary to check that no other fault codes are stored, especially those related to the transmission fluid temperature. In that case, you should take the appropriate corrective action.
Refer to the vehicle's service manual for the location and routing of the turbine speed sensor wiring and inspect these components. Check the circuit for damage, such as corroded connectors or burned wires. Repair or replace as required.
Disconnects the PCM and performs resistance, ground, reference voltage, and continuity checks for the Turbine Speed Sensor The results obtained from these checks, you should compare to the manufacturer's specifications and, if inconsistencies are detected, make repairs as required.
Uninstall the Turbine Speed Sensor and check it for excessive accumulation of metal particles. If this is the case, proceed to make the appropriate adjustments.