Spark plug inspection (Hyundai Accent LC)

Visual inspection of the working part of the spark plugs can indicate the condition of the engine.

If the nose of the insulator is covered with a black coating, this indicates that the mixture is too rich. If the coating is black and oily, this indicates engine wear and the need for inspection and repair. If the nose of the insulator is covered with a light brown coating, the mixture composition is optimal and the engine is in good condition.

If the nose of the spark plug insulator is clean and white, without any deposits, this indicates that the mixture is too lean. This also indicates that the plug is too hot, i.e. the heat from the central electrode is being slowly removed. If this is the case, the fuel mixture must be adjusted or the plug must be replaced.