If the spark plugs exhibit the following symptoms, it may indicate a malfunction: Difficulty in starting the car, whether cold or hot, often requiring multiple attempts. Engine shaking, noticeable while driving. Reduced power, feeling significantly weaker than usual. Increased fuel consumption. Stalling. Failed exhaust emissions. Common causes and diagnosis of spark plug failures: Common issues that prevent spark plugs from working include: Incorrect spark plug gap adjustment. A gap too small limits the contact area between the spark and the air-fuel mixture and suppresses flame kernel growth due to the electrode's quenching effect, 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 the crack, preventing sparking at the electrodes. Electrode carbon buildup, causing the central electrode to leak current instead of sparking to the side electrode. Excessive carbon buildup can short-circuit the spark plug, damaging the insulator and rendering it faulty. Damaged electrodes. Prolonged electrical erosion or chemical corrosion from combustion gases can break or detach the electrodes, preventing sparking. Low insulation resistance. This reduces the ignition voltage across the spark gap, weakening or completely disabling the spark. Short-circuited 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 prevents that cylinder's spark plug from firing. Burnt contact points. This causes all spark plugs to fail, preventing engine startup and operation. Faulty spark plugs should be replaced promptly. Replacement steps: Open the hood, remove the engine's plastic cover, and disconnect the high-voltage wires, marking each cylinder's position to avoid confusion. Use a spark plug socket to remove each spark plug, ensuring the surrounding area is free of debris like leaves or dust. Insert the new spark plug into the hole, hand-tighten it first, then use the socket to secure it. Reattach the high-voltage wires in the correct firing order and replace the cover. Replacement interval: Typically every 40,000-60,000 km under normal maintenance, but this varies by brand and engine. Refer to the owner's manual for specifics.
