How can I diagnose a faulty spark plug on my Audi 80?

I suspect one of my spark plugs may be causing issues in my Audi 80. How can I confirm which spark plug is faulty and what steps should I take to replace it?

To diagnose a faulty spark plug, first remove the spark plug wires and visually inspect each one for signs of damage or wear. Next, use a spark plug tester to check the spark plug's output. Finally, if there is no spark or a weak spark, it may be time to replace the spark plug.

Before replacing a spark plug, make sure you have the correct replacement for your specific model of Audi 80. I recommend referring to the owner's manual or consulting with a mechanic for assistance.