Spark plugs have been around since the beginning, and play as important a role now as they did a hundred years ago. It’s a good idea to replace them as a set at regular intervals, but sometimes one will go bad sooner than the rest for one reason or another. How do you know if you have a bad spark plug? Here are some indicators, from Harold's Used Auto Parts Inc in Philadelphia, PA.

At Harold's Used Auto Parts Inc in Philadelphia, PA, we are here to maintain and repair your vehicle. We’re also here to help you keep your car, truck, or SUV in good shape and running strong. “Bad gas” is often cited as the cause for a variety of issues - but what does that mean, and what can you do?