Can You Continue Driving with One Bad Spark Plug?

[OscarMarie]

You can continue driving with one bad spark plug, but only for a short period. If not replaced promptly, it may lead to malfunctions and accelerate engine damage or even complete failure. If a spark plug is found to be faulty, it must be replaced immediately to maintain the engine's optimal performance and improve fuel efficiency. A faulty spark plug can cause an increase in deposits on the plug. After driving for some time, deposits will accumulate on the top of the spark plug insulator and the electrodes, which in severe cases can prevent the engine from functioning properly. A faulty spark plug can also disrupt the ignition system, leading to incomplete combustion of the air-fuel mixture. This results in harmful substances being emitted without full combustion, and an abnormal ignition system with incomplete combustion will also lead to fuel wastage.

[SabrinaAnn]

I've been repairing cars for over a decade and have seen many car owners ask if they can keep driving with faulty spark plugs. The answer is crystal clear: Absolutely never force it! When a car loses a spark plug, it results in cylinder misfiring, causing unburned gasoline to rush directly into the exhaust pipe. Not only does fuel consumption skyrocket by 30%, but it can also damage the catalytic converter—replacing a new one costs two to three thousand yuan. More critically, the engine will shake violently, making the steering wheel hard to hold steady, and sudden loss of power on the highway can be life-threatening. I had a client who stubbornly insisted on driving to pick up their kids, only to break down halfway, with even the piston rings ending up deformed. Even for a short trip to the repair shop, the uneven engine load can cause connecting rods to bend, and the repair costs would be enough to buy dozens of new spark plug sets.

[DelSavannah]

Last week my car suffered from spark plug failure, and the feeling of misfiring was unbearable. During startup, the whole car vibrated like a massage chair, with the tachometer needle dancing wildly. Only when driving did I realize the acceleration was sluggish – even flooring the gas pedal couldn't catch up to electric scooters. The most annoying part was the backfiring 'pop pop' sounds from the exhaust, making me the target of impatient honking at red lights. I immediately pulled over and called roadside assistance. The mechanic warned that continuing to drive would cause fuel injector carbon buildup and more expensive repairs. Lesson learned – I now keep an emergency toolkit in the trunk. If the diagnostic shows spark plug trouble codes, I shut off the engine immediately and call for help. Never gamble with safety.

[StGideon]

Spark plug failure may seem like a minor issue, but it actually affects the entire vehicle's lifespan. A single cylinder misfire will cause the ECU to continuously enrich fuel injection in other cylinders, inevitably damaging the oxygen sensor. Carbon buildup in the combustion chamber increases like a snowball, potentially clogging valves within half a month. Worse yet, unburned gasoline dilutes the engine oil, causing oil that should last 10,000 kilometers to emulsify and deteriorate after just 3,000 kilometers. I learned this the hard way with my old Mercedes - the engine overhaul cost me 45,000 yuan. Now whenever I encounter engine vibration, I immediately check the ignition system. I make it a rule to replace all four spark plugs without fail at 80,000 kilometers. After all, a 200-yuan preventive measure is far more economical than tens of thousands in repair costs.