You can drive a car with a misfire, but only for a short distance to a repair shop

A misfire means one or more cylinders in your engine are not firing properly — the spark plug ignites, but the fuel does not burn as it should. The car will run rough, lose power, and shake. You can operate the vehicle to get it to a mechanic, but continuing to drive it normally will damage the engine and make the repair more expensive.

The longer you drive on a misfire, the more unburned fuel flows into the exhaust system and the catalytic converter. That raw fuel heats up and can crack the converter, which costs $800 to $2,500 to replace. Continuing to drive also risks damage to the engine itself — unburned fuel washes down cylinder walls and thins the oil, which reduces lubrication and can lead to bearing wear.

If your check engine light is on and you feel a rough idle or hesitation under acceleration, get the car scanned for the misfire code and have it repaired within a few days. Driving it to work every day for a week will cost you more in the long run.

Key Takeaways

  • A misfire is safe enough to drive to a repair shop, but not safe for regular commuting or long trips.
  • Unburned fuel from a misfire damages the catalytic converter and thins engine oil, leading to expensive repairs if ignored.
  • The check engine light will display a misfire code (P0300, P0301, P0302, etc.) that a mechanic can read with a scanner.
  • Common causes are a bad spark plug, a failing ignition coil, a clogged fuel injector, or low fuel pressure.

What a Misfire Does to Your Engine

When a cylinder misfires, the fuel-air mixture does not ignite. That unburned fuel exits the cylinder and enters the exhaust manifold, where it can ignite in the hot exhaust system. This creates a popping sound and visible flame from the tailpipe, and it overheats the catalytic converter.

The catalytic converter is designed to burn off emissions, not raw fuel. Repeated misfires cause the converter's internal honeycomb to crack or melt. Once damaged, it cannot be repaired — it must be replaced. A single misfire for a few miles will not destroy it, but a misfire that goes on for days or weeks will.

Unburned fuel also drips down into the oil pan and dilutes your engine oil. Thin oil does not protect moving parts as well, and bearings can wear faster. In severe cases, this leads to bearing failure and engine seizure.

How to Identify a Misfire

A misfire feels like the engine is stuttering or bucking under load. You may notice a rough idle when stopped at a traffic light, hesitation when you press the gas pedal, or a loss of power on the highway. The steering wheel or seat may vibrate noticeably.

The check engine light will turn on. When you take the car to a mechanic or auto parts store, they will scan the engine computer and retrieve a misfire code. Common codes are P0300 (random misfire), P0301 (cylinder 1 misfire), P0302 (cylinder 2 misfire), and so on. The specific code tells the mechanic which cylinder is misfiring or whether it is happening randomly across all cylinders.

Some misfires are intermittent — they happen only under certain conditions, like when the engine is cold or under heavy acceleration. Others are constant. Either way, the code will be stored in the computer and visible to a scanner.

Common Causes of a Misfire

The most common cause is a bad spark plug. Spark plugs wear out over time and lose the ability to create a strong spark. If your car has over 30,000 miles since the last spark plug change, worn plugs are the first thing to check. Replacing them is inexpensive — usually $100 to $300 for all four or six plugs.

A failing ignition coil is the second most common cause. The coil generates the high voltage needed to fire the spark plug. When it fails, one or more cylinders will not fire. A coil replacement costs $150 to $400 per coil, depending on the vehicle.

A clogged fuel injector prevents fuel from reaching the cylinder. Carbon buildup inside the injector narrows the opening, and the fuel spray pattern becomes weak or uneven. A fuel system cleaning or injector replacement may be needed, costing $50 to $300.

Low fuel pressure from a failing fuel pump or a clogged fuel filter can also cause a misfire. If the fuel pressure is too low, the injector cannot spray fuel properly, and the cylinder will not fire. A fuel pump replacement is more expensive — $400 to $800 — but fuel filter replacement is cheap, around $50 to $150.

When to Stop Driving and Call a Tow Truck

Stop driving when ready if the misfire is severe enough that the car is hard to control, if the check engine light is flashing (not just steady), or if you smell fuel or see smoke from the engine bay. A flashing check engine light means the misfire is severe enough to damage the catalytic converter in real time, and you should not drive the car at all.

If the misfire is mild — you feel a slight roughness but the car still accelerates and steers normally — you can drive it slowly to a nearby repair shop. Keep the engine at low RPM and avoid hard acceleration. Do not take the highway or drive for more than 10 or 15 miles.

If the repair shop is far away or you are not sure how bad the misfire is, call a tow truck. The cost of a tow ($75 to $150) is less than the cost of a catalytic converter replacement.

What a Mechanic Will Do

The mechanic will connect a diagnostic scanner to your car's engine computer and read the misfire code. This tells them which cylinder or cylinders are misfiring. They will then perform a visual inspection of the spark plugs, ignition coils, and fuel injectors to look for obvious problems like a loose wire or a damaged plug.

If the spark plugs look worn, they will replace them and retest. If the plugs are new, they will test the ignition coil with a multimeter to see if it is producing the correct voltage. They may also check fuel pressure with a gauge to rule out a fuel system problem.

In some cases, the mechanic may need to perform a fuel injector cleaning or replace the fuel filter. If the misfire code is P0300 (random misfire) and the plugs and coils are good, a fuel system issue is likely.

Frequently Asked Questions

Is it safe to drive with a misfire to the mechanic?

Yes, if the misfire is mild and the repair shop is close. Drive slowly, avoid the highway, and keep the trip under 15 miles. If the check engine light is flashing or the misfire is severe, do not drive — call a tow truck instead.

Can a misfire fix itself?

No. A misfire is caused by a mechanical or electrical failure, and it will not go away on its own. The problem will get worse the longer you drive, and the damage to the catalytic converter will increase.

How much does it cost to fix a misfire?

It depends on the cause. Spark plugs cost $100 to $300. An ignition coil costs $150 to $400. A fuel injector cleaning costs $50 to $300. A fuel pump replacement is the most expensive at $400 to $800. A mechanic's diagnostic fee is usually $100 to $150.

Will a misfire cause my car to fail an emissions test?

Yes. A misfiring engine produces excess emissions and will not pass a state emissions test. The check engine light will also prevent you from passing, since most states require the light to be off and no active codes in the computer.

Can I drive with a misfire if I ignore the check engine light?

The light will not go away, and the problem will not improve. Ignoring it only increases the damage to your catalytic converter and engine. Have the code scanned and the misfire repaired as soon as you can.