W140 Maintenance Light?
 

Even though the W140 isn't the next Mercedes on my list I can't help but look at them since they have come down in price so much. I've looked at a number of nice ones for under $10K. Last week I took a 1999 S600 for a test drive and when I started the vehicle a little light came on just below the speedometer. It was a little wrench and said "-400" and it went off after about 5 seconds. I would assume the vehicle is overdue for some maintenance? Is there any way of telling what maintenance is necessary? The mileage is just over 57,000.

I has gone 400 miles beyond the suggested service, the basic service is oil, oil filters and probably some maintenance items. If you take it in your dealer will want to check this, that oil the hinges, check the spare, and lots of things. Typically any where from the $ twos to the high fours. The brake fluid should be changed, trans fluid, etc. These are suggested but and should think about it. I would go in for a check and have them tell you what they think and then decide. They can reset the counter.

Seeing as how I like to perform maintenance procedures is it possible to reset the counter myself?

Yes
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