I believe the oil filter from a M44 is used on some M42s.
You have a M42 1.8L. An M42 is OBD-I.
From
Pelican Parts For BMWs equipped with OBD I, you can read the codes using a system that is built into the car.* For OBD II compliant cars (1996 and later), the codes can only be read using a scan tool (more on this later).
To read codes for an OBD I car, you start by turning the ignition key on (do not start the engine) and pressing the gas pedal to the floor five times within a period of five seconds. * If you proceeded correctly, then the check engine lamp will light on for five seconds, then blink off, then blink on for 2.5 seconds, and then go off for another 2.5 seconds.* After this, the computer will start to show you the trouble fault codes that are stored.