BMW On Board Diagnostics
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.
As always, if anyone
has any questions about this or any other technical article, do not
hesitate to email me at firstname.lastname@example.org.
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