2018 Mercedes-Benz SL450 No Start Diagnosis Cost

Generally, a "no-start" vehicle will either fail to crank or fail to start while cranking. No-start conditions can arise from many locations on the vehicle, including the engine, transmission, grounding wires in any part of the vehicle, battery, alternator and more.

Most vehicles will fail to start at some point. Most commonly, vehicles fail to start due to an issue in the starting and charging system, such as a bad battery, alternator, battery cable or starter. Unfortunately, there's no way to anticipate when a no-start condition will occur, but proper maintenance and inspections can help prevent them.

The technician will try to start the vehicle and observe what happens. There may be no sound, a clicking sound, or the car may sound like it's cranking normally but just failing to catch. The dash lights should dim when the key is turned, and the fuel pump should be heard at some point before the key is turned to start the engine. In most cases, no-start problems are caused by the starting and charging system. The technician can test this system using a diagnostics machine. If the starting system functions properly, the technician will use a different scanner to read OBD trouble codes, and will test other components or read sensor inputs. 

Correcting most no-start problems usually involves replacing the alternator, starter or battery, cleaning connections, ignition system repairs, or fuel system repairs. But because there are so many potential causes, the diagnosis is key to understanding how expensive the repair will be.

Most people with car knowledge can learn to diagnose the starting and charging system, which is the root of most no-start issues. But with so many potential causes, this diagnosis is usually best left to a professional.