Can I drive with a bad coil?

Yes, you can sometimes drive a short distance with a bad ignition coil to reach a safe location or repair shop, but it’s risky and not recommended. A failing coil typically causes a cylinder misfire, which can quickly overheat and damage the catalytic converter, reduce power, and increase the chance of stalling. If the check-engine light is flashing, stop driving and arrange a tow.

What “a bad coil” actually means

An ignition coil transforms battery voltage into the high voltage needed to fire the spark plugs. Modern vehicles usually use coil-on-plug (one coil per cylinder) or a coil pack serving multiple cylinders. When a coil fails, the affected cylinder(s) misfire—wasting fuel and stressing the catalytic converter. Older vehicles with a single coil may not run at all if the coil fails. Note: Diesel engines and pure EVs don’t use ignition coils, so the question doesn’t apply to them.

Common signs your ignition coil has failed

Drivers often notice performance changes first. Modern engine computers also store diagnostic trouble codes (DTCs) that identify misfires and coil faults, which can be read with an OBD-II scanner.

• Check-engine light on; a flashing light indicates an active severe misfire (codes like P0300–P0308 for misfires, P0351–P0358 for coil circuit faults).
• Rough idle, shaking, stumbling, or stalling, especially under load.
• Reduced power, sluggish acceleration, and poor fuel economy.
• Fuel smell from the exhaust, occasional popping/backfiring, or sulfur/“rotten egg” odor (catalyst distress).
• Hard starting or no-start if multiple cylinders are affected (coil pack or single-coil systems).
• Moisture, oil in spark plug wells, cracked coil boots, or heat-related coil breakdown.

These symptoms point to incomplete combustion. The more severe the misfire, the higher the risk of drivability issues and expensive emissions-system damage.

Risks of driving with a bad coil

Operating with a misfire isn’t just inconvenient—it can be costly and unsafe. Even a few miles under heavy load can harm components.

• Catalytic converter damage from raw fuel entering the exhaust; overheating can happen in minutes and may melt the catalyst substrate.
• Oxygen sensor fouling and eventual failure due to excess unburned fuel.
• Engine wear from fuel washing cylinder walls, diluted engine oil, and fouled spark plugs.
• Safety risks: reduced power for merging or passing, rough running, or stalling in traffic.
• Emissions and legal issues: you’ll fail inspection where applicable; a flashing MIL indicates a condition that should not be driven.

Because repair costs escalate quickly once the catalyst is damaged, avoiding unnecessary driving is the safest and most economical choice.

How far can you drive?

If the check-engine light is flashing, don’t continue—pull over safely and call for a tow. If the light is steady and the vehicle runs reasonably, you can usually drive a few low-load miles to a nearby shop, avoiding high speeds, steep grades, and heavy throttle. On coil-on-plug engines, you may “limp” on one misfiring cylinder; on vehicles with a single coil or some coil packs, the engine may run very poorly or not at all. Some vehicles will disable fuel to the misfiring cylinder to protect the catalyst, but you should still head straight to service.

What to do if you must drive

If driving is unavoidable, take precautions to minimize damage and risk.

1. Confirm the issue if possible with an OBD-II scan for misfire (P030x) or coil (P035x) codes; if the MIL flashes, stop and tow.
2. Drive gently: keep RPM and throttle low, avoid hills, and stay off highways.
3. Go directly to a repair facility via the shortest safe route; don’t make extra stops.
4. Avoid towing, hauling, or full-throttle acceleration, which rapidly overheats the catalyst.
5. Consider roadside assistance or towing—often cheaper than replacing a catalytic converter.

These steps won’t fix the problem but can reduce the odds of turning a simple coil replacement into a major exhaust-system repair.

DIY checks and temporary steps

Basic inspections can help confirm a bad coil and prevent repeat failures. Only work on a cool engine and disconnect the battery if required by your vehicle’s service procedures.

• “Swap test” on coil-on-plug engines: move the suspected coil to another cylinder; if the misfire code follows (e.g., P0302 to P0304), the coil is likely bad.
• Inspect spark plugs and coil boots for cracks, carbon tracking, oil, or moisture; replace damaged parts and use dielectric grease on boots as specified.
• Check for oil in plug wells (often a valve cover gasket issue) or coolant leaks—fix the leak to avoid recurring misfires.
• Examine connectors and wiring for corrosion, loose pins, or broken tabs; repair as needed.
• Verify battery and charging health; low voltage can aggravate misfires under load.

These are diagnostic aids, not cures. If a coil is cracked or shorted, replacement is the remedy—and plugs should be evaluated and often replaced at the same time.

Repair options and typical cost

Prices vary by vehicle and parts quality, but prompt repair is usually straightforward and far cheaper than catalyst replacement.

• Ignition coil (coil-on-plug): about $40–$150 for mainstream parts, $100–$250+ for premium/OEM; 0.5–1.0 hours labor per coil in many engines.
• Coil pack (serves multiple cylinders): roughly $150–$400 parts; 0.5–1.5 hours labor.
• Spark plugs: about $8–$20 (copper) or $10–$30 (iridium/platinum) each; 1–2+ hours labor depending on access; replacing plugs with coils is commonly recommended.
• Oxygen sensors: around $100–$300 each if fouled by misfires.
• Catalytic converter: roughly $1,000–$3,000+ for most modern vehicles (OEM units can be higher).

Addressing a misfire early—coil and plug—can prevent four-figure exhaust repairs and restore performance and fuel economy.

When not to drive at all

Some warning signs mean it’s safer and cheaper to stop immediately and tow the vehicle.

• Flashing check-engine light, heavy shaking, or the car can’t maintain speed.
• Strong fuel or sulfur smell, visible exhaust “puffing,” or a glowing red catalytic converter area.
• Loud backfiring, repeated stalling, or multiple-cylinder misfires.
• You’re in heavy traffic, severe weather, or on high-speed roads where a stall would be dangerous.

In these conditions, continuing to drive risks both safety and major component damage—towing is the prudent choice.

Summary

You can sometimes limp a short distance with a bad ignition coil, but it’s ill-advised and can quickly become expensive. A misfire risks damaging the catalytic converter, O2 sensors, spark plugs, and even the engine’s oil. If the check-engine light is flashing—or drivability is severely affected—stop and tow. Prompt diagnosis and replacement of the faulty coil and any worn plugs typically resolve the issue and prevent larger repairs.

What happens if the ignition coil is bad in a car?

Difficulty Starting: A failing coil can weaken or prevent the spark entirely, resulting in hard starts or no-start conditions. Illuminated Check Engine Light: Fault codes related to misfires (like P0301-P0306) may point directly to ignition issues.

Can coil cause car jerking?

You Can’t Get Your Car to Run Smoothly
This makes your car shake while idling and jerk or sputter while you’re driving. A bad coil can cause your engine to misfire, and the only solution is to get that coil replaced.

How long can you drive with a broken coil?

Can you drive with a broken coil spring? No, you cannot drive your vehicle if the boil spring is broken. It is illegal to drive a vehicle that isn’t safe and road legal – and having little or no control over a vehicle when it turns or drives over uneven surfaces can lead to dangerous situations.

How long can you drive with a bad ignition coil?

You should only drive a vehicle with a bad ignition coil for the shortest distance possible, such as to a nearby repair shop, to avoid severe and costly engine damage. Driving with a faulty coil causes misfires, leading to unburned fuel entering the catalytic converter, potentially destroying it, and also dilutes the engine oil, which can cause internal engine damage. 
Why driving with a bad ignition coil is risky

• Engine Misfires: Opens in new tabThe engine cylinder with the bad coil will not ignite the fuel-air mixture, causing the cylinder to act as a brake rather than producing power. 
• Unburned Fuel: Opens in new tabThe unburned fuel bypasses the piston rings, washing away the oil and causing wear on the cylinder walls. 
• Diluted Engine Oil: Opens in new tabUnburned fuel can mix with the engine oil, diluting it and hindering proper lubrication. This can damage the engine’s bearings. 
• Catalytic Converter Damage: Opens in new tabThe unburned fuel can reach the catalytic converter, causing it to overheat and potentially disintegrate. 
• Engine Stress and Vibrations: Opens in new tabMisfires create vibrations that can stress the engine’s crankshaft and bearings, potentially leading to spun bearings. 
• Reduced Fuel Efficiency and Performance: Opens in new tabA misfiring engine will also suffer from reduced power and poor fuel economy. 

What to do if you have a bad ignition coil

1. Limit Driving: Only drive the vehicle as much as absolutely necessary to get to a qualified mechanic. 
2. Drive Gently: Avoid quick acceleration and high RPMs, which can worsen the damage. 
3. Replace the Coil Promptly: Get the bad ignition coil replaced as soon as possible to prevent further damage and potentially expensive repairs.