Trouble Code 03 - Coolant Temperature Sensor
WARNING: This page is about a different car, the 1989 BMW 325is, 1989 BMW 325iX, and 1989 BMW 325i. However, it is still accessible from the selected car via links, so may be relevant.
The coolant temperature sensor is faulty or the engine is running too hot or too cold. This is due to a faulty cooling system component. To correct this test the coolant temperature sensor and cooling system components.