The component that detects combustion concerns through vibration.

The component that detects combustion concerns through vibration.

• A. Knock sensor
• B. Spark plug
• C. Camshaft sensor
• D. Oxygen sensor

Answer: (A)

When combustion isn’t proceeding smoothly, abnormal high-frequency vibrations travel through the engine. The knock sensor is designed to pick up these vibrations. It’s a piezoelectric device attached to the engine block or cylinder head that generates a signal when it detects detonation or abnormal engine knocking. The engine control unit uses this signal to retard timing and adjust fueling, reducing peak pressures and protecting the engine from damage. Spark plugs initiate combustion but don’t detect knock. Camshaft sensors track valve timing rather than combustion vibrations. Oxygen sensors measure the exhaust’s oxygen content to fine-tune the air–fuel ratio, not knock detection.

When combustion isn’t proceeding smoothly, abnormal high-frequency vibrations travel through the engine. The knock sensor is designed to pick up these vibrations. It’s a piezoelectric device attached to the engine block or cylinder head that generates a signal when it detects detonation or abnormal engine knocking. The engine control unit uses this signal to retard timing and adjust fueling, reducing peak pressures and protecting the engine from damage.

Spark plugs initiate combustion but don’t detect knock. Camshaft sensors track valve timing rather than combustion vibrations. Oxygen sensors measure the exhaust’s oxygen content to fine-tune the air–fuel ratio, not knock detection.