How can you tell if your automatic transmission speed sensor has gone haywire? Just take a look at your speedometer. If you're rocketing down the freeway and your needle still says you're going 0, then you need to slide under your auto and inspect your automatic transmission speed sensor. And, in case you need to replace your bum stock automatic transmission speed sensor, AutoAnything is here with amazing deals on factory-grade new parts. You get our 1-year lower-price guarantee and free shipping.