can a bad coil pack keep car from starting

[SanJace]

Yes, a failed ignition coil pack can absolutely prevent your car from starting. It's a common cause of a no-start condition, especially if the engine cranks normally but refuses to fire up. The ignition coil's job is to transform the battery's low voltage (12 volts) into the thousands of volts needed to create a spark at the spark plugs. If one or more coils are dead, that spark isn't generated, meaning the fuel in the cylinders won't ignite.

You'll often notice warning signs before a complete failure. Symptoms include the check engine light being illuminated, the engine misfiring (running rough with shaking or sputtering), a significant loss of power, and difficulty accelerating. A diagnostic code scanner can usually confirm a coil problem with codes like P0300 (random misfire) or specific cylinder misfire codes (e.g., P0301).

Diagnosing a bad coil is straightforward. A mechanic might perform a spark test to see if the spark is present. They can also check the coil's primary and secondary resistance with a multimeter to see if it's within the manufacturer's specifications. Replacing a faulty coil pack is a standard repair. While you can sometimes drive with a single misfiring coil (though it's not recommended), a failure in the coil that serves multiple cylinders or a complete failure of the main coil pack will leave you stranded.

Symptom	Description	Why it Happens
Engine Cranks but Won't Start	The starter motor turns the engine over, but it doesn't fire and run.	No spark is being sent to the spark plugs, so fuel cannot ignite.
Check Engine Light	The vehicle's computer detects a problem in the ignition system.	Codes like P0300 (random misfire) or P0351 (ignition coil "A" primary/secondary circuit) are stored.
Engine Misfire	The engine runs unevenly, shakes, or sputters, especially at idle.	One or more cylinders are not firing correctly due to a weak or absent spark.
Reduced Power & Poor Acceleration	The car feels sluggish and struggles to gain speed.	With cylinders misfiring, the engine cannot produce its full power.
Rough Idling	The engine shakes noticeably and the RPMs may fluctuate while stopped.	Unburned fuel from misfiring cylinders disrupts the engine's smooth operation.
Poor Fuel Economy	You find yourself filling up the gas tank more often.	Incomplete combustion wastes fuel, reducing miles per gallon.

[OJackson]

For sure. If that coil is totally dead, you're not going anywhere. It's like trying to light a gas stove with a dead lighter – you have fuel, but no spark to set it off. The car might crank and crank, but it just won't catch. Before it dies completely, you'll probably feel the engine shaking and sputtering. It's a pretty common headache, but thankfully, swapping out a coil is usually a quick and relatively inexpensive fix.

[StOmar]

From a pure function standpoint, a bad coil pack is a definitive cause for a no-start. My focus is on the electrical pathway: battery provides low voltage, the coil pack is the essential step-up transformer, and the spark plug is the actuator. If the coil fails, the high-voltage circuit is broken. The engine control unit (ECU) may even log fault codes related to ignition circuit performance. The repair is typically component replacement, but diagnosing which specific coil has failed is key to avoiding unnecessary parts costs.