Why is my check engine light only on when I open the door and the car is running?

Hi, this is Bo, an auto expert on RepairPal's Car Genius team! Now that’s a quirky one—your check engine light only comes on when you open the door while the car’s running? On your 1997 Mazda Protege, that sounds more like an electrical gremlin than a typical engine issue. It could be something as simple as a ground wire or a loose connection, possibly between the door wiring and the dash. Before your next smog test, I’d have an electrical specialist take a peek at the door wiring and connections. If you need any further advice or want help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554!