Q: Input turbine speed sensor B has stopped working

Hello and thank you for your question. It sounds like the input turbine speed sensor B has failed or lost connection to the engine control module (ECM). You will first need to check the wiring to the sensor and see if there is any debris or corrosion at the circuit causing a blockage of power. If the circuit has power and the engine is working well but the transmission is still in limp mode, then the sensor has failed. I recommend replacing the sensor if this is the case. If the sensor has been replaced and the wiring is in good shape, then the ECM has lost its programming or the ECM has failed, in which case the ECM should be flashed or replaced. If you need assistance troubleshooting the input speed to the transmission, then you can always seek out a professional technician, such as one from YourMechanic, to help you with your vehicle.