Which issue may cause the engine to start in any gear on an auto-shift transmission vehicle?

The issue that can cause the engine to start in any gear on an auto-shift transmission vehicle relates to the start enable relay. In vehicles equipped with an auto-shift transmission, the start enable relay is a safety feature designed to prevent the engine from starting unless the transmission is in a specific gear, usually neutral or park. If this relay is defective, it may fail to correctly detect the transmission's gear status. As a result, the system may not restrict the engine from starting while the vehicle is in gear, posing a significant safety risk.

In contrast, the brake light switch primarily monitors the status of the brake lights and doesn't directly influence the vehicle's ability to start in gear. Low engine oil pressure is more related to engine lubrication issues than to transmission functions, and worn fuel injectors affect engine performance but not starting behavior with respect to transmission gear. Thus, the defective start enable relay is the issue that directly connects to the problem of engine starting in any gear.