I recently purchased a 2009 S550 4 magic with 75,000 miles. I took it for the state inspection, which I failed. There's only 1 reason to fail-emissions. It was a faulty bank1 sensor 1 oxygen sensor. by the time I returned to the dealer where I bought the car, it was about 9-10 days. He fixed the problem. After about 5 miles from his store, the battery light came on. The speed indicator line disappeared by 75%. The command center turned off automatically. Before going home I had to make 1 stop. I made the stop, turned the car off etc. I got ack in the car & it's been running fine ever since (since Thursday, I had the problem fixed on Wed. Today is Sunday).

I'm thinking of adding a gas additive to clean out any stuff that may have accumulated in the engine. I keep seeing Chevron Techron as being the best (Mercedes approved) or going to a Mercedes dealership for their gas additive.

Any comments/info would be greatly appreciated

Thanks

On Sunday, the check engine light now comes on. I think it's a minor problem. Hate to go to Mercedes because they charge $150/hr. Could this be another sensor or carbon build up on the cylinders?

 

Hello and welcome to the forum! Before spending money on parts, I would suggest getting the codes pulled. This should give you a definitive answer as to where the issue is. Hope this helps and best of luck!