Spark plug failure manifests in the following ways: Difficulty in starting the car, both cold and warm starts are problematic, often requiring multiple attempts. Engine shaking occurs while driving. Reduced power output, noticeably weaker than usual. Increased fuel consumption. Engine stalling. Failed exhaust emissions. Common causes and diagnosis of spark plug failures: Several factors can lead to spark plug malfunction: Incorrect spark plug gap adjustment. A gap too small limits the contact area between the spark and the air-fuel mixture, suppressing flame kernel growth despite sparking, resulting in weak sparks and ignition difficulties. A gap too large may exceed the ignition system's voltage capacity, preventing sparking. Cracked spark plug skirt. High-voltage current leaks through cracks, preventing sparking at the electrodes. Electrode carbon buildup, causing the center electrode to leak current sideways instead of sparking to the side electrode. Excessive carbon deposits can short-circuit the spark plug, damaging the insulator and rendering the spark plug useless. Electrode damage. Prolonged electrical erosion or chemical corrosion from combustion gases can break or detach electrodes, preventing sparking. Low insulation resistance of the spark plug. This reduces the ignition voltage across the spark gap, weakening or completely eliminating the spark. Short circuit in high-voltage wires. Leakage in the wire from the ignition coil to the distributor prevents the entire engine from starting, while leakage in the wire from the distributor to a spark plug stops that cylinder's spark plug from firing. Erosion of platinum contacts. This prevents all spark plugs from firing, making the engine unable to start or run normally. Faulty spark plugs should be replaced promptly. Replacement steps are as follows: Open the hood, remove the engine's plastic cover, and detach the high-voltage wires, marking each cylinder's position to avoid confusion. Remove the spark plugs one by one using a spark plug socket, cleaning any external debris like leaves or dust. Insert the new spark plug into the hole, hand-tighten it first, then use the socket to secure it. Reinstall the high-voltage wires in the correct firing order and replace the cover. Spark plug replacement interval: Typically every 40,000-60,000 km under normal maintenance, but this varies by brand and engine. Always refer to the owner's manual for guidance.
