Q: Powertrain warning lamp.

Hello. The powertrain warning light, commonly referred to as the check engine light can come on for many reasons. If the engine computer detects an issue with the engine management, fuel, ignition, or emissions systems, it will set off the check engine light to notify the driver of the issue. In some instances, such as with minor emissions issues, the vehicle may display the warning light, and still run fine, however will not pass an emissions test. The trouble codes can be retreived using a compatible scan tool, and will likely reveal some insight on what the issue may be. I would recommend having a professional technician, such as one from YourMechanic, come to your location to (diagnose the cause of the check engine light)[https://www.yourmechanic.com/services/check-engine-light-is-on-inspection].