The 2004 Honda Civic has four spark plugs.
In more detail, the 2004 Civic lineup is powered by four-cylinder engines—the most common being a 1.7-liter inline-four in most trims and a 2.0-liter unit in the Si variant. Regardless of the exact engine, the layout requires one spark plug per cylinder, totaling four plugs. Honda used a coil-on-plug ignition system for these engines, meaning there are four ignition coils, one for each cylinder, paired with the four plugs.
Key points to remember about the 2004 Civic spark plug arrangement:
- Four spark plugs in the engine (one per cylinder).
- Each cylinder has its own ignition coil in a coil-on-plug configuration.
- All major 2004 Civic engines—1.7L and the 2.0L Si—use four plugs, though some variants may vary slightly by market.
- When replacing plugs, use the recommended heat range and torque as specified in the owner's manual or service guide.
In short, regardless of trim, the 2004 Honda Civic uses four spark plugs—one for each cylinder.
Summary
The answer is four. The Civic’s four-cylinder engines require one spark plug per cylinder, for a total of four plugs, with four corresponding ignition coils in a coil-on-plug setup. Always consult the owner’s manual for exact maintenance intervals and torque specifications.