Why is my Vauxhall Astra engine making a loud knocking noise?

I recently noticed that my Vauxhall Astra's engine is making a loud knocking noise while idling. What could be causing this issue and how can I fix it?

The loud knocking noise could be due to a malfunctioning or worn-out engine component, such as a piston or connecting rod. It's important to get your car checked by a mechanic as soon as possible to prevent further damage to the engine.

Another potential cause for the knocking noise could be low engine oil levels. Check your oil level and top up if necessary. If the noise persists, it's best to get your car inspected by a professional.

If the knocking noise only occurs when the engine is cold, it could be a sign of worn-out engine bearings. These should be replaced by a mechanic to avoid more serious engine problems.