I recently purchased a 2012 E550 with Keyless Go, but only one FOB. I have contacted several dealers about purchasing another FOB and have been quoted prices around $370. There seems to be some question between the dealers about programming the new FOB. Some say the new FOB requires no additional programming. Most say it does require additional programming and they charge an hour labor in addition to the price of the FOB. One dealer told me if my Keyless GO system was working correctly, programming the new FOB consists of putting it in the ignition and letting the car recognize it and they do not charge for this. If it doesn't recognize they charge $180 to diagnose and repair the issue.

If my Keyless GO system is working correctly (which it is) should the new FOB require an hour labor to program it?

Any insight would be appreciated.

It requires programing by the dealer. No exceptions.

If so, I am curious why a dealer told me if the keyless go system was working correctly no programming was needed. Have you purchased an extra fob? If so, I assume you were charged a service fee?

I haven't purchased a new key personally but know people who have. They all needed to be programed...its expensive. I don't know why the dealer told you it would program itself. Think about it for a minute. It would be too easy to change keys. What kind of security would that provide.?
So this is one of those times you need to pay to play.

FWIW, my two Mercedes are a W210 and a W211. I bought a new key fob for each when I purchased. I did not take the cars to the dealer; in each case, I picked up the new key fob at the dealer, took the fob home, inserted the fob into the ignition, and started the car. Programming of the car at the dealer was not required; the new key itself, however, is programmed by the Mercedes unit (in Dallas, TX, IIRC) to work exclusively with your EIS. On the W211, keyless-go worked and still works.

Your EIS will have eight potential keys that can be programmed to the car. If the first key is lost, provide proof of ownership to Mercedes and purchase a new replacement key. You can lose up to seven keys and still have a valid key. Lose the eighth key, however, you're going to need some new electronics. The only programming the dealer will do is to "nullify" the lost key information in your car's electronics so the old key will not work in your car anymore. Additionally, the dealer might set up the car so when you open or close the door, the steering wheel and/or seat will move to an exit/entry position. I have this feature on my W211's old key fob but not on the new key fob. Looked into programming it myself but just never got around to it over the last three years...

Every dealer I contacted said I needed to bring the car in when I picked up the fob, saying they needed to verify the fob works. This may be the extra charge that some are talking about. Mine has the seat memory, but it is not activated when the door is opened, so there would not be that issue. If anyone purchased a fob lately, would you mind sharing the cost. I assumed the fob would be the same for all 2012 W212, A207 and C207 variants, but that appears not to be the case. I thought it was part number 950-62-02-9999, but that appears to be for the sedan only. Anyone know the part number for the cabrio? It seems the old part number was 212-766-45-06, but it is no longer active. When I called around the cheapest I have found for the cabrio is $372 including tax, but no service fee.

$370 sounds right about what I paid for my W211's key. The dealer is the only game in town when you need a key so you're not going to find much of a discount. For the part number for your car, the only way to order parts is you want to provide the VIN; that ensures you are aware of the latest parts or parts that are unique to your build. You'd be mildly surprised just how many notes are in the EPC database....

The next used Mercedes I purchase, I now know to insist the seller provide a functioning two-fob set or knock $400 off the price of the car to account for my time and parts cost to get a replacement...

Did some more searching on this topic. Here's a link to a 94-page Mercedes Benz document that explains the Drive Authorization System. Yes, it appears that it can require a dealer to verify everything functions so as to prevent customer complaints.

http:/benzbits.com/DAS.pdf