Do diesel engines use spark plugs?

Diesel engines, unlike gasoline engines, do not use spark plugs to induce combustion. Instead, they rely solely on compression to raise the temperature of the air to a point where the diesel combusts spontaneously when introduced to the hot high pressure air. The high pressure and spray pattern of the diesel ensures a controlled, complete burn. read more

Introducing a spark plug in a diesel engine is very inefficient, if you can visualize the scenario of a spark plug ignition during compression, this is what is going to happen, the required ignition temperature of the mixture is already achieved from the fuel injector while in compression, further with the ignition the temperature will only rise. read more

So in petrol engine, the air fuel mixture is sent into the engine cylinder and the mixture is ignited by the spark generated by the spark plug. Whereas in diesel engine the air is compressed initially then the fuel i.e., diesel is injected into the cylinder. read more