This morning about 20 minutes after start my '01 C240 displayed this message: Undervoltage Consumer Defective!. The fault than clears when the car is started and again reappears some 15-25 minutes later. I also noted a noise coming from the passenger side of the engine when I start the car in the morning. Chirping short (and intermittent) noise, reminds me of the noise that waterpump bearing makes when busted. Has someone experienced something similar. Is this type of alternator serviceable like old ones were - I mean regarding replacement of voltage regulator? I could not locate voltage regulator for this model.

Thank you.

I've seen a few false warnings in my '01 C320's display but not that one. I would doubt that the alternator is the culprit. The auxiliary water pump for the CC system is mounted on the front of the radiator header tank so when the noise is heard again, lift the hood to localize it. Also, check the multi-rib drive belt for looseness.

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Roger E.

Yeah, I've seen also quite a few false alarm messages, some even funny like the one for Tele-Aid which I never had enabled, and countless front signal bulbs failures (bulbs always OK). I got used to the "moodyness of my car" , but this electrical issue scares me, cause once I got stranded (it was not MB) as I ignored warnings re. alternator issue.
I will check the auxiliary water pump, the noise is very rare and short -lasting when first started in the morning. The belt is fine and properly tensioned, I examined it the other day because I have a new replacement belt (the car has 80k).

My car's favorite is "crankcase overfilled, proceed to MB workshop" or some such. The first time this appeared, I thought it possible that coolant was flowing into the crankcase and of course it wasn't. The dealer reset the oil level parameters a bit but still on occasion I see it. I just dismiss it. Another is "ESP (including ABS) Unavailable". A restart fixes that.

We'll see what built in faults my '08 C300 has. If it ever shows up.

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Roger E.

Can't wait for manual transmission C300, should be a huge bit more agile than my C240.....