First Law of Thermodynamics: Energy is conserved!

Everytime the flux field is interrupted by the flywheel segments, the pickup produces a small voltage. The input impedance to the EZL is high, but not infinite, so a slight amount or current and thus, energy, is transfered and this will eventually consume the pickup's magnetic flux. "Permanent magnets" aren't really permanent, depending on how they are used.

Whether the reduction in magnetic flux in, say 150K miles of driving, is one percent, ten percent, or fifty percent I don't know, but it may be an issue.

I don't believe in replacing parts unless a reliable test shows that they are faulty, but it sometimes takes fairly expensive test equipment to run the tests that the average DIYer may not own or have access to.

A scope can be used to monitor the output voltage wave form of the 02 sensor, and given the cost of an O2 sensor, I believe they should be tested rather than replaced, apriori. A professional should have the equipment and testing the O2 sensor only takes a few minutes, but my suspicion is that many shops don't bother to look at the O2 sensor output waveform before replacing them. Many shops just want to replace parts rather than doing diagnostics. Even some dealers fall into this category. We here these stories frequently on this board.

Likewise, the Mercedes service literature has a voltage at engine speed spec for the crankshaft position sensor, and a scope should be able to handle this test, either with an inductive pickup on the CPS signal cable or directly connecting the CPS signal cable to the scope. And such a test will only take a few minutes.

I've never tested my CPS because I have no reason to suspect it may be faulty, but I have inspected the output waveform of my O2 sensor.

Duke