Recently my 500sl took to not starting. So far it has always started when cold. Then occasionally it will turn over very well but it will not start, indidcating the battery is not the fault. In the owners manual it states there is an ign. lock out that wont let it start but should give an error message in the odometer something like "start err", which I did not get. I scanned it for codes and found none but at the time the engine was starting. Either the engine starts and runs normally or it does not start at all. I wonder if the crank or cam sensor maybe going away? If so how do you check them? Any help would be appreciated

 

Have you checked your sparkplug already?If its tip is already blackened,whell you have to look for another pair. Or if isn't it could be your Mercedes Benz ignition coil.It looks like a small box with a cylinder inside.A great amount of voltage is needed in order to ignite the spark plugs of your Mercedes and trigger the fuel burning in the combustion chambers. The voltage that is needed can be produced by the ignition coil, and also an important part of the ignition system. Without this coil, it would be impossible for the spark plugs to generate the spark that will be used to ignite the compressed air-fuel mixture.