P0717 Buick -what does this code mean?

Question

I'm getting a PO717, and a PO716 trouble code. What do these mean?

Answer 1

Both codes are related to the input shaft speed sensor on the transmission. Here is a brief description and you likely need a new input shaft speed sensor to solve this.

The Automatic Transmission Input Speed Sensor (A/T ISS) is a permanent magnet with a coil of wire wound around it. The A/T ISS mounts in the transmission case facing the drive sprocket of the input shaft. As the drive sprocket is driven by the turbine shaft, an AC signal is induced in the input speed sensor. Higher vehicle speeds induce a higher frequency and voltage at the sensor.
An air gap of 0.08-2.12 mm (0.0032-0.834 in) must be maintained between the sensor and the drive sprocket to insure proper operation of the A/T ISS. The A/T ISS is used by the PCM in order to control line pressure, Torque Converter Clutch (TCC) apply and release and transmission shift patterns. This sensor is also used to calculate the appropriate gear ratios and TCC slippage.
If the PCM detects a low input speed while the vehicle and engine speeds are high, then DTC P0717 sets. DTC P0717 is a Type B DTC.