P0300 Chevy Spark: Random or Multiple Cylinder Misfire Detected

Chevy Spark P0300 Random Misfire Diagnosis

Quick Answer: What is P0300?

On a Chevy Spark, the P0300 code triggers when the Engine Control Module (ECM) detects that multiple cylinders are failing to spark properly. Because the Spark's 4-cylinder engine is very small and revs high, it is extremely tough on ignition components. The most common cause is a cracked or failing ignition coil pack or severely worn spark plugs.

Emergency Warning: If your Check Engine Light is flashing, you must pull over safely and shut off the car. A flashing light means raw fuel is being dumped directly into the exhaust. On a tiny engine like the Spark's, this will melt the catalytic converter in minutes, turning a $100 repair into a $1,000 disaster.

Common Symptoms

Severe Shaking: The car vibrates violently at stoplights (the Spark already vibrates slightly by design, but a misfire makes it extreme).
Loss of Power: The car struggles to accelerate and cannot reach highway speeds.
Flashing Check Engine Light: Blinking under load or acceleration.
Stalling: The engine may shut off entirely when the AC is turned on.

Most Likely Causes

Failing Ignition Coil Pack (50%): On older Sparks (2013-2015), the coils are a single heavy block. The plastic housing cracks and the electrical spark "jumps" to the engine block instead of the spark plugs.
Worn Spark Plugs (35%): Cheap copper or heavily worn plugs with a gap that is too wide for the coil to jump.
Dirty Fuel Injectors: Restricting fuel flow, causing a "lean" misfire.
Vacuum Leaks: A cracked PCV hose allowing unmetered air into the tiny intake manifold.

Detailed Repair Cost Breakdown

Estimates for Chevy Spark (1.2L and 1.4L engines) in the US market:

Component / Task	Aftermarket Part	OEM ACDelco Part	Labor Time
Ignition Coil Pack / Coils	$50 - $80	$120 - $160	0.5 hr (Easy DIY)
Spark Plugs (Set of 4 Iridium)	$35 - $50	$65 - $90	0.5 hr
Spark Plug Wires (1.2L only)	$25 - $40	$55 - $80	0.2 hr

How to Fix P0300 on a Chevy Spark

1. Inspect the Coil Block for "Arcing"

If you have an older 1.2L Spark, the ignition coils are housed in a single black square block on the side of the engine. Wait until it is dark outside, start the engine, and look closely at the coil block. If you see tiny blue sparks jumping from the black plastic to the metal engine block, the housing is cracked. You must replace the entire coil pack assembly.

2. Change Plugs and Coils Together

Because these tiny engines work so hard, ignition components wear out in unison. If your spark plugs have over 60,000 miles on them, the widened gap places immense stress on the ignition coils. Replacing just the coils without replacing the old spark plugs will cause the new coils to burn out prematurely.

3. Always Use Iridium ACDelco Plugs

Do not buy cheap copper spark plugs for a Chevy Spark. The ECM is calibrated specifically for the resistance of OEM ACDelco Iridium plugs. Using the wrong spark plug will result in an immediate return of the P0300 code and a rough idle.