RPM sudden drop/ jerk at idle
I own a BMW 525i, 2007 (E60), done 41000 miles. At the cold start up takes the RPM to 1000 and then slowly starts coming down. At about 700 rpm it suddenly takes a sudden dip to below 500 and quickly jumps back to 600-or 700. Then its settles at 600 or about. The car also does the same when it is at idle say at a traffic signal. it can take a sudden jerk from 600-700 to below 500 and again back.
BMW service center insist that some sensor is to be changed. earlier they replaced the fuel sensor but it did not help. Now they want too change the NO2 sensor. Expensive proposition that is. Anyone who has the same experience and may have resolved it may advise.