Abstract: In this work, we have performed investigation on the susceptibility of automotive engine speed sensor to electrical fast transient (EFT) pulse via injection method. The criterion for determining the susceptibility threshold was proposed on the basis of the function and electromagnetic effects of speed sensor. A Hall speed sensor was taken as the research object. Using our self-developed speed test device, EFT pulses were injected into the speed sensor through its power wire and signal wire, respectively, and the failure thresholds were correspondingly obtained. The failure of speed sensor shows random property under the interference of EFT pulse. And the failure rate conforms to the cumulative distribution function of normal distribution. When the EFT was injected into the sensor from its power wire instead of from the signal wire, the breakdown threshold was much lower and breakdown bandwidth was narrower. Moreover, the repetition frequency affected the susceptibility of speed sensor significantly. With the increase of repetition frequency, the susceptibility of speed sensor decreased, and eventually became stable.