It's your engine, letting you know there's a problem somewhere under the hood. If the smooth rumble you're used to coming from your engine is replaced with a repetitive tapping or pinging sound that becomes louder and faster as you accelerate, that's a classic sign of engine knock.

What does it mean when my engine is making a knocking noise?

The knocking sound often occurs when the air-fuel mixture is incorrect, which causes the fuel to burn in uneven pockets rather than uniform bursts. Left untreated, it can cause damage to the piston and cylinder wall. A knocking sound can also be caused by a lack of lubrication in the upper cylinder head area.

Is it bad if your engine is knocking?

Knocking can damage the surface of the piston, the cylinder walls or the crankshaft bearings, all of which are expensive to repair. Modern computer-controlled injection systems can correct your fuel mixture to prevent knocking, but at the cost of engine performance.