Did you know that your BMW 3 Series has an internal diagnostic program built into the computer? Not many people know about this. On the BMW 3 Series, there is a way that you can diagnose common engine problems without having to purchase a code tool or take it to the dealer to have it scanned. This is one of those neat little features of the Service Indicator Computer; the series of lights directly under the tachometer and speedometer that remind you to change the oil and perform service. In this tech article, I will provide you with the procedure for checking the fault codes and what the codes mean. This guide will help you to diagnose any possible problems with your car.
This article is written for both the BMW E30 and E36 3 Series cars (up to 95) and should work on both models where a Service Indicator Computer is used. I will go over the small differences between the early and late cars, as they differ slightly. Keep in mind that this procedure will not work on early cars with Motronic 1.1.
Now on the E30 models, get in the car and put the key in the ignition and turn it to the second turn or “ON” position, but do not start the car. Now, press the accelerator pedal all the way to the floor, then let it release all the way back. Now repeat the depress/release cycle 4 more times fairly quickly, but not too fast. It may take some time to get this timing down correct. It should only take you a few seconds to do this. What this does is activate the wide-open throttle switch and the idle switch 5 times. This then sends a signal to the Motronic ECU to send fault codes to the Service Indicator Light.
On the E36 models, the procedure works the same way, but the timing at which you press/release the gas pedal is faster than on the E30. Just keep at it, and you will eventually get the correct speed.
Watch the “Check Engine” light. It should blink once, and then start blinking a series of four numbers. For instance, say this is a sequence you see… the light blinks once, then twice, then four times and lastly four times. If you read it correctly this means that the SI light is reading out the code 1244 (faulty camshaft sensor) The codes appear as a series of flashes for each digit. The flashes indicating one digit are about one second apart, the next digit will appear after a couple seconds interval. If there are no faults in the car, the computer will flash out the number 1444.
Here is the list of codes and what they indicate.
1215 Air Mass Sensor
1222 Lambda Control 1
1256 Fuel Injector 6
1271 Ignition Coil 1
1275 Ignition Coil 5
