What it does Quick sparkplug diagnosis: a penstyle spark plug tester that verifies whether a spark plug is firing. It helps you detect dirty, fouled, or damaged spark plugs fast so you can take the right action. Key benefits Fast troubleshooting: identify misfiring plugs on the spot to avoid extended diagnostic time or unnecessary part replacement. Simple operation: insert the tester between the spark plug and the ignition lead; if the tester shows a spark, the plug is functioning. Durable design: constructed from metal and plastic for long service life; the body resists breakage and the cord is flexible for easy routing. Wide compatibility: works with all types of internal combustion engines, including cars, trucks, motorcycles, and lawn mowers. Features and performance Penstyle tester that connects directly between spark plug and ignition cord. Clear spark indication confirms plug performance during cranking or running. Robust metal/plastic construction for repeated garage or field use. Flexible test lead lets you reach tight engine bays and awkward spark plug positions. How to use Turn off the engine and follow basic safety precautions. Disconnect the ignition lead from the spark plug. Connect the tester between the spark plug and the ignition lead. Crank the engine briefly; visible spark at the tester means the plug is firing. Practical applications Car maintenance: quickly check spark plugs during routine tuneups or when diagnosing rough idle and misfires. Motorcycle troubleshooting: test individual cylinders after a fall or when a bike runs unevenly. Lawn mower and small engine service: verify plug condition during seasonal maintenance to ensure reliable starting. Compatibility and materials Compatible with all internal combustion engines that use conventional spark plugs. Made of metal and plastic for durability; includes a flexible cord for easy handling. Use this spark plug tester when you need a straightforward, reliable check of spark plug condition without complex equipment.