If you hear a spark knocking or pinging noise from your engine or exhaust, it usually means that fuel is igniting in the cylinder at the wrong time. This is often referred to as preignition or detonation. Left unresolved, it can damage pistons, valves, and other internal components. An inspection will determine the cause and protect your engine from costly repairs.

What does spark knocking or preignition mean?

Spark knock happens when the air-fuel mixture in the engine ignites too early or unevenly. Instead of a smooth burn, it creates small explosions that sound like knocking, pinging, or rattling from the engine bay or exhaust.

Common causes of spark knocking or preignition

• Low-octane or poor-quality fuel
• Carbon build-up inside the combustion chamber
• Incorrect ignition timing
• Faulty knock sensor
• Lean air-fuel mixture (too much air, not enough fuel)
• Overheating engine
• Worn or damaged spark plugs

Why do you need to fix this problem quickly?

Continuous spark knock increases engine stress and heat, which can damage pistons, cylinder walls, and valves. This can lead to expensive engine repairs or failure if ignored.

How do you know when to get it checked?

You should book an inspection if:

• You hear pinging or rattling noises when accelerating
• The noise gets louder under heavy load or climbing hills
• Your Check Engine Light is on
• Engine performance feels rough or sluggish
• You experience frequent overheating

What happens during an assessment?

A mechanic will:

1. Listen for knocking and confirm the source
2. Check ignition timing and engine temperature
3. Inspect spark plugs, knock sensor, and ignition components
4. Scan the ECU for error codes
5. Test fuel quality and air-fuel mixture
6. Advise on necessary repairs or adjustments

How much does it cost to fix?

Costs vary depending on the cause. Spark plug replacement may cost $150–$300, while knock sensor replacement is typically $250–$500. More serious issues like carbon cleaning or timing repairs can range from $400–$1,200+.

Is it unsafe to drive with spark knocking?

Yes. Persistent spark knock can cause serious engine damage. While the car may still run, it should be inspected and repaired as soon as possible to avoid costly repairs.