can you drive a car with a missing spark plug

[OCamille]

No, you should not drive a car with a missing spark plug. Operating a vehicle in this condition can cause immediate and severe damage to the engine. The primary risk is to the ignition coil, which is designed to fire against the compression pressure within the cylinder. With the spark plug missing, the coil discharges into open air, leading to extreme voltage overload. This almost certainly will destroy the ignition coil. Furthermore, the open spark plug hole allows unfiltered air and debris into the cylinder, potentially scoring the cylinder walls and contaminating the engine oil. The engine will run extremely rough, with a significant loss of power, and unburned fuel can damage the catalytic converter, a very expensive component to replace.

The severity of the symptoms depends on the engine configuration. A four-cylinder engine missing one plug will run on three cylinders, which is highly unstable. A larger V6 or V8 might run, but poorly. The following table outlines the potential consequences and associated repair costs, which far exceed the minimal cost and time of replacing a single spark plug.

Potential Consequence	Description of Damage	Estimated Repair Cost (USD)
Ignition Coil Failure	The coil overheats and burns out due to lack of resistance.	$150 - $400 (part + labor)
Engine Misfire	Unburned fuel enters the exhaust system.	N/A (symptom, not a repair)
Catalytic Converter Damage	Unburned fuel ignites inside the cat, causing meltdown.	$1,000 - $2,500+
Cylinder Wall Scoring	Debris enters the cylinder, damaging internal components.	$1,500 - $3,000+ (engine rebuild)
Oil Contamination	Fuel and moisture dilute the engine oil, reducing lubrication.	$50 - $100 (oil change)

The only acceptable action is to have the vehicle towed to a repair shop or, if you have the tools and knowledge, to install a new spark plug on the spot. Driving even a short distance is a gamble with your engine's health. The risk of turning a simple $20 fix into a multi-thousand-dollar repair is simply too high.

[LeEverly]

Absolutely not. Think of it like this: your engine is a sealed system. That hole where the spark plug goes is now a direct opening for dirt, moisture, and anything else to get sucked right into the heart of your engine. It's begging for a catastrophic failure. On top of that, the ignition coil that's supposed to fire that plug will burn itself out in no time. You'll be adding a several-hundred-dollar coil replacement to your bill. Call for a tow; it's the only smart move.

[DeViolet]

I learned this the hard way with my old truck. It started shaking violently and had no power. Turns out a spark plug had worked itself loose and fallen out. I was tempted to just drive it home, but my mechanic friend told me in no uncertain terms to shut it off immediately. He explained that the constant misfire was dumping raw gas into the catalytic converter, which could destroy it. I had it towed, he put a new plug in for twenty bucks, and it ran fine. Driving it could have cost me over a thousand.