I have a 1988 BMW 325IX. The miles per gallon gauge located at the bottom of the gauge cluster has become inoperable. My go to shop indicates that it might be a defective main circuit board but can not say for sure. Another shop thought that it might be in the wiring that has something to do with the oxygen sensor. Anyone out there have any experience with this kind of problem. Looking for sound direction on having this repaired. The local bmw dealer tells me that this part was not available for my car, and that it had to be removed, repaired, and reinstalled. Any and all assistance in getting this problem alleviated will be most appreciated. Thank you in advance.
The mpg gauge runs off a circuit board inside the cluster. There are two main issues I see with this the batteries on the board start to fail on a tracer on the board has failed. You can replace the batteries from the board but requires soldering. You can get a replacement board that will come with new batteries. The O2 sensor affecting the mpg is doubt full mainly because there are many inputs and calculations done on the SI board for the gauge to work not just an O2. Hope this helps if you have another e30 swap the clusters and see if the other cluster MPG gauge works then you know its nothing in your car doing in.
