Have your wife carry the second key with her, if it does it again see if the other key will start it.
Gilly

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Good idea. Will do. (But I hope the new CPS fixed it.)

Thanks Gilly.

I'm sure that it will.

FWIW, the CPS is available as a non-MB branded Bosch part for a whole lot less than the dealer would charge you for the branded part.

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In regards to the key being a possiblity, if that IS the cause of the problem, when the engine is cranking but not starting, the odometer display spells out the words "start error". That's where she'd want to try the other key. It means the key which isn't allowing the start has a bad transponder "chip" in it, not too uncommon. That's about the only reason you'd get that display (it could be another type of DAS problem tho), it means there is a problem with DAS (driver authorization system), it won't show this for a problem like the CPS or a bad fuel pump for example, this is very specific to a problem with DAS.
Gilly

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I've started a thread on how to evaluate the CPS at Benzworld. Here's the link:

http://www.benzworld.org/forums/w163-m-class/1282808-cps-evaluation.html?highlight=cps+evaluation

Here part of the post:

The following is my opinion and I welcome any comments and suggestions. I'm posting this because I am getting the impression that many people point to the CPS as a problem when their vehicle doesn't start or stalls. Even though this area is a potentional cause for no starts or stalling one should not assume that it is the only reason and many replace a perfectly good sennsor for no other reason than to hope that it solves their problem. The CPS can fail for many reasons and they do fail. Heat can be an cause for CPS failiure (I've tested one on a bench with a torch applied to it and measure the effects of heat on it's resistance and there is a noticable change.) but it can also be flywheel damage, debris on sensor, installation, etc. The only definitive way to rule out the CPS is testing which is not difficult. Measuring the resistance is a poor test which is too general. The best way to test is to use a scope (oscilloscope) to observe the waveform and output. Please see the attached image from a W126 WIS. On this application, the output (Us) must be greater than 1 volt. If the computer does not see this minimum requirement then it won't know when to time the car! I do not have the W163 WIS so I cannot compare the differences but the concept should be the same.

Comments?

DL

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