What does the 2002 Nissan Altima code p1574 mean?

The P1574 Code on a 2002 Nissan Altima indicates there's a problem with the ASCD vehicle speed sensor. This code shows up when the ECM notices a discrepancy between two vehicle speed signals that falls outside the specified range. One common indicator of a faulty speed sensor is unusual operation of the automatic transmission. If the VSS is not functioning properly, the transmission might display issues such as delayed shifts, rough shifts, and limited gear functionality. A malfunctioning speed sensor can lead to poor performance or even prevent your car from running. The speed sensor, also called the vehicle speed sensor or VSS, measures the output of the transmission. This information directly correlates to the speed of your vehicle and how quickly you're moving. This data is then used to adjust engine functions like air and fuel ratios, shifting times, as well as for diagnostic purposes.