Have the car towed to a MB dealer so their Service Department can read the codes to determine what's wrong. Their prices may be a bit higher than your friend's shop, but the dealer should be able to diagnose the problem and get you back on the road. I'd go back to the seller for some money toward the repair. In the future have a PPI (Pre-Purchase Inspection) done by a MB-trained tech before you buy any used MB. When you post a thread it would help to state the mileage on your 1997 C280. It may need the fuel filter replaced ... when was the last time it was changed? It's advisable to buy a used MB with a documented service history so you know how well the car has been maintained.

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Fred Hoelzle