Can you drive if you need spark plugs replaced?

Yes, you can usually drive to a repair shop to have spark plugs replaced, but you should not push your car hard or drive far if the plugs are worn or the engine is misfiring. If you notice symptoms, limit driving and arrange service promptly.

Signs that spark plugs may need replacement

These symptoms help you assess whether replacement is due and how urgent your trip to a shop should be.

• Rough idle or engine misfires


• Reduced acceleration and power


• Lower fuel economy and higher emissions


• Check Engine Light or trouble codes related to ignition


• Difficulty starting or frequent stalling

If you notice these signs, plan a timely replacement to protect your engine and catalytic converter.

Is it safe to drive to a repair shop?

Guidance on how to approach driving when plugs may be worn or failing, and when to seek help.

• If the engine is misfiring or running rough, avoid long trips and consider towing or roadside service to prevent damage.


• If you are within the normal maintenance interval and the engine runs smoothly, a short, cautious trip to a nearby shop is usually acceptable.


• Avoid aggressive driving, high speeds, or heavy loads while symptoms persist, as these can worsen ignition problems.


• Keep an eye on the Check Engine light; if it remains illuminated after a reset or recheck, stop and diagnose before continuing.

In uncertain cases, it's safer to arrange towing rather than risking a breakdown on the road.

What to expect during spark plug replacement

Here’s what typically happens during a professional replacement and what you should expect from the service.

1. Diagnosis and confirmation that the plugs (and sometimes the wires or coils) are due for replacement


2. Selection and installation of the correct plugs for your engine, including proper gaps and torque


3. Inspection or replacement of ignition wires or coil packs if they’re part of the system


4. Clearing any codes and allowing the engine management to re-learn idle and fuel trim


5. Test drive and final inspection to ensure smooth operation

Most spark plug replacement jobs take roughly 30 to 90 minutes on modern engines, depending on access and whether ignition components also need service.

Maintenance schedule and replacement frequency

Typical replacement intervals by plug type

Ignition plug life varies by design. The following ranges reflect common expectations, but always check your owner’s manual or service bulletin for your specific vehicle.

• Copper plugs: often around 30,000 miles (48,000 km)


• Platinum plugs: typically around 60,000 miles (96,000 km)


• Iridium or long-life plugs: commonly around 100,000 miles (160,000 km)


• Note: oil consumption, fuel quality, and driving style can shorten life; some performance or specialized engines use different intervals

Always verify exact intervals for your car and use the recommended plug type and torque settings when replacing.

Summary

Driving with worn spark plugs is usually possible for a short, careful trip to a repair shop, but you should treat it as a maintenance urgency. Symptoms like misfires, rough idle, or weak acceleration mean you should seek service promptly to avoid further damage. Replacement timing depends on plug type and vehicle, with typical lifespans ranging from 30k to 100k miles. When in doubt, consult your owner's manual or a qualified mechanic and avoid risky driving conditions until the plugs are replaced.

Is it safe to drive if you need new spark plugs?

A broken spark plug can cause engine misfires, rough idling, and potential damage to the cylinder head. Driving 100 miles with a broken plug risks further engine damage and poor fuel economy. If immediate replacement isn't possible, drive gently at low speeds and avoid heavy acceleration.

What happens if a spark plug goes bad while driving?

Yes -- spark plugs can fail while driving, and when they do they typically cause misfires, loss of power, rough idling, poor fuel economy, or engine hesitation. Failure can be sudden or progressive depending on cause and driving conditions.

What happens if you wait too long to replace spark plugs?

If you don't change spark plugs on time, you can experience poor performance, reduced fuel economy, and difficulty starting your car. Over time, this can lead to more serious engine problems, such as misfires, rough idling, and even damage to the catalytic converter or other engine components.
 
Performance and fuel economy issues

• Reduced performance: Your engine may feel sluggish, acceleration can be poor, and you might experience engine misfires (jerking or shaking). 
• Rough idling: The engine may shake or "hunt" for an idle speed, especially when stopped. 
• Increased fuel consumption: A weak spark can lead to incomplete combustion, causing your engine to use more fuel and lowering your gas mileage. 

Starting and other problems

• Difficulty starting: Worn spark plugs can make your car hard to start, or it may not start at all. 
• Engine knocking: In severe cases, worn plugs can lead to engine knocking or pinging sounds. 
• "Check Engine" light: Your car's computer may detect the misfires and trigger the check engine light. 

Potential long-term engine damage 

• Catalytic converter damage: If the spark plugs cause persistent misfires, unburnt fuel can enter the exhaust system and damage the catalytic converter, leading to a costly repair. 
• Engine wear: In the worst-case scenario, continuous misfires and improper combustion can cause excess wear on engine components like pistons and cylinder walls. 

How long can I drive with bad spark plugs?

You should not drive with bad spark plugs for any significant length of time, especially if you notice any performance issues like misfires. While the car may still run for a short distance, continuing to drive can cause serious and expensive damage to the engine's catalytic converter, cylinder walls, and other components. The safest course of action is to replace the bad spark plugs immediately. 
Risks of driving with bad spark plugs

• Engine misfires: This is one of the most common symptoms of bad spark plugs and can lead to a domino effect of problems. 
• Catalytic converter damage: Misfires can send unburnt fuel into the exhaust system, causing the catalytic converter to overheat and become damaged. 
• Reduced fuel efficiency: Your engine won't burn fuel as efficiently, leading to a decrease in gas mileage. 
• Difficulty starting: The engine may take longer to start or may have trouble starting at all. 
• Poor performance: You may experience rough idling, sluggish acceleration, and general poor engine performance. 
• Damage to other components: The misfiring cylinder can wash the oil off the cylinder wall, leading to increased wear on the cylinder wall and piston rings. The ignition coils can also be stressed and fail. 

When to stop driving immediately

• If your Check Engine light is flashing, this indicates a severe misfire and you should stop driving the vehicle as soon as it is safe to do so. 
• If you notice any of the performance issues listed above, it's best to avoid driving and get the car repaired as soon as possible. 

What to do

• Replace them immediately: Spark plugs are a routine maintenance item, and replacing them when they are bad is the best way to protect your engine from more costly damage. 
• Drive gently if absolutely necessary: If you must drive a short distance, do so at low speeds and avoid heavy acceleration. 
• Don't ignore the problem: Even if the issues seem minor now, driving with bad spark plugs can lead to catastrophic engine failure in the future.