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      06-09-2011, 08:24 AM   #15
WallyF
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Drives: 2006 325xi & 2011 128i conv
Join Date: Oct 2005
Location: Fort Wayne, IN

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Brake sensor Replacement is necessary

I replaced the rear pads per this DYI on my 2006 325xi. I tried to reset the onboard computer (OBC). I was able to reset the value from 3400 miles to minus 15,000 miles. Of course I got a red warning service indication and red "Brake" light. After some reading on the forum, I found that the sensor has a variable resistance and must be replaced if one wants the OBC to be reset to a positive number of miles.

I replaced the brake sensor (BMW #34356789445) and was able to reset the computer to 31,000 miles. All of the red warnings went away.

So, if you want the E90 onboard computer (OBC) to function correctly when brake pads are replaced, the sensor must be replaced!!!

I measured the DC resistance of the new sensor and old sensor.
New sensor = 0.5 ohms
Old sensor = 450 ohms
So, as the sensor wears down, the resistance goes up. This is in contrast to the E46 sensor that is an open(infinite ohms) or short(zero ohms) situation.

Will the author of this DYI and make sure the DYI is updated.

Thanks

Wallyf
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