Why want my 2000 s430 mecedes benz start after putting fuel injector cleaner in

First question: Did it run before you added the injector cleaner or did you add it because it would not start? If it was not running right before you added the cleaner, the cleaner is not your problem. It is highly unlikely that a standard off-the-shelf injector cleaner would cause any damage. It is possible for it to move some dirt in the system and POSSIBLY clog one injector, but highly improbable that it would take the entire system down. If anything, you have stirred up something in the tank and clogged a fuel filter and/or strainer on the pump.

I would first change the main fuel filter - it is located under the car and is rather easy to change. If it is the strainer, the pump has to be removed.

More common on Mercedes V8s of that year is either a crank/cam sensor or an immobilizer issue (ECU not recognizing key). Either way, it would be a good idea to have the codes ran on the car, not just the OBD codes, but get a shop that can scan the actual Mercedes codes.

Best of luck!
-Scott
www.EuroPartsPlus.com