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P2765 — Inputturbine Shaft Speed Sensor B Circuit

Manufacturer-specificPowertrain (engine & transmission)

The P2765 code indicates a malfunction in the electrical circuit of the 'B' input/turbine speed sensor. This sensor measures the rotational speed of the transmission's input shaft or torque converter turbine, providing critical data for shift timing and torque converter lockup. A circuit fault can lead to erratic shifting, transmission slippage, or limp mode.

Symptoms

What causes it — most likely first

1. Faulty input/turbine speed sensor B

The sensor itself may have failed internally due to heat, vibration, or age, causing an open or short circuit.

2. Damaged or corroded sensor connector

Moisture intrusion, dirt, or corrosion at the connector can create high resistance or intermittent contact.

3. Wiring harness issues

Chafed, broken, or shorted wires between the sensor and the TCM/PCM can disrupt the signal.

4. Low or contaminated transmission fluid

Insufficient fluid level or degraded fluid can affect sensor operation and lead to erratic readings.

5. Faulty transmission control module (TCM) or powertrain control module (PCM)

A module failure is rare but can misinterpret sensor signals. This should be considered only after all other causes are ruled out.

How it's diagnosed

  1. Check transmission fluid level and condition; top off or replace if low or dirty.
  2. Visually inspect the input/turbine speed sensor B and its wiring harness for damage, corrosion, or loose connections.
  3. Use a scan tool to monitor live sensor data while driving; look for erratic, missing, or implausible speed readings.
  4. Test the sensor's resistance with a multimeter and compare to manufacturer specifications.
  5. Check the sensor circuit for shorts to ground, shorts to power, or open circuits using a wiring diagram.
  6. If all other tests pass, suspect a TCM/PCM fault, but verify with professional diagnostic equipment before replacement.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)

Frequently asked

Can I drive with a P2765 code?

It is not recommended, as the transmission may shift erratically or enter limp mode, potentially causing further damage.

Is the input/turbine speed sensor the same as the output speed sensor?

No, the input sensor measures speed before the gearset, while the output sensor measures after. They serve different purposes.

Will replacing the sensor always fix the code?

Not necessarily. Wiring or connector issues can cause the same code. Proper diagnosis is essential to avoid unnecessary parts replacement.

Could the PCM be the cause of P2765?

It is extremely rare. The PCM is often misdiagnosed for this code. The sensor, wiring, or connector are far more likely culprits.