What Do The Spark Plugs Do? (2001, 2002, 2003, 2004, 2005 1.7L Honda Civic)

The spark plug is probably one of the smallest ignition system components on your vehicle, yet tasked with a tough job. And this job is to deliver the spark (the ignition coil creates) into the cylinder to ignite the air-fuel mixture.

Quite a few things can cause the spark plug to fail, so in this article, I'm going to answer some of the most commonly asked questions about the spark plug on the 1.7L Honda Civic.

APPLIES TO: This article applies to the following vehicles:

  • 1.7L Honda Civic DX: 2001, 2002, 2003, 2004, 2005.
  • 1.7L Honda Civic EX: 2001, 2002, 2003, 2004, 2005.
  • 1.7L Honda Civic GX: 2001, 2002, 2003, 2004, 2005.
  • 1.7L Honda Civic HX: 2001, 2002, 2003, 2004, 2005.
  • 1.7L Honda Civic LX: 2001, 2002, 2003, 2004, 2005.

What Does A Spark Plug Do?

In a nutshell, the spark plug's job is to ignite the air-fuel mixture within the cylinder it's connected to.

It does this by transmitting a spark from its center electrode to its side electrode.

And as mentioned earlier, this spark is the spark created by the ignition coil (that the spark plug is connected to).

Symptoms Of A Bad Spark Plug

The most obvious symptom of a bad spark plug is a misfire problem.

This misfire will cause the fuel injection computer to illuminate the check engine light with a misfire diagnostic trouble code.

You'll see one or more of the following misfire diagnostic trouble codes (DTCs):

  • P0300: Random Cylinder Misfire.
  • P0301: Cylinder #1 Misfire.
  • P0302: Cylinder #2 Misfire.
  • P0303: Cylinder #3 Misfire.
  • P0304: Cylinder #4 Misfire.

Besides a misfire DTC, you'll also see one or more of the following symptoms:

  • Rough idle.
  • Bad gas mileage.
  • Extended engine cranking (engine takes longer than usual to start).
  • A heavier than normal exhaust smell coming out of the tailpipe.
  • The engine is not as peppy as it used to be.
  • Hesitation when you accelerate the vehicle on the road.

What Causes A Spark Plug To Stop Working?

Unfortunately, quite a few things can cause the spark plug to stop transmitting spark and igniting the air-fuel mixture within its cylinder.

The most common problems causing a spark plug to fail are:

  • Normal wear and tear. In other words, they simply wear out.
  • Carbon deposits blocking the air gap between the center and side electrodes.
  • Damage caused by the installation process (for example, during a tune-up).

Engine oil burning inside the cylinder is the cause of carbon deposits forming and blocking the spark plug's center and side electrodes.

Carbon deposits blocking the spark plug's electrodes are usually caused by engine oil that's burning inside the cylinder the spark plug is connected to.

You can quickly identify an oil-burning engine because:

  • They have blue smoke coming out of the tailpipe (when the engine is running or under load).
  • They need to have engine oil added regularly.

How Do I Know My Spark Plugs Need Changing?

The spark plugs on your 1.7L Honda Civic will eventually wear out and will need replacement. Unfortunately, the spark plugs will need to be replaced before they wear out in many cases.

Generally, you'll replace the spark plugs because:

  • You've removed them and are showing signs of heavy wear and tear.
  • They're causing an engine performance problem.
  • You're following a recommended spark plug change interval.

Which Spark Plugs Should I Buy?

When your 1.7L Honda Civic left the factory, it was equipped with either NGK or Denso brand spark plugs.

These are the spark plugs I recommend you buy and install when it's time to replace them.

Having said that, there are plenty of after-market spark plug brands you can buy and install. If you go this route, you'll need to buy spark plugs that are specifically designed for your particular Honda Civic.

Should I Use 100,000 Mile Spark Plugs?

Spark plugs advertised as having a service life up to 100,000 miles have platinum or iridium-tipped electrodes. Regular spark plugs, which have copper electrodes, do not last that long.

The catch here is that if the engine is in perfect working condition (e.g., it's not burning oil), these spark plugs will give you a service life of about 100,000 miles.

But if you got a high mileage engine that is burning oil, you're not going to see anywhere near 100,000 miles on those spark plugs. Carbon buildup will eventually close the air gap between the spark plug electrodes and cause a misfire.

Important Tips And Suggestions

TIP 1: Replace the spark plugs with a completely cold engine. The cylinder head on your Honda Civic's 1.7L engine is made of aluminum. This means that you've got to remove the spark plugs from a completely cold engine.

Why? Because you run the risk of damaging the spark plug hole threads if you remove the spark plugs from a hot engine.

Trust me; this is a nightmare that you want to avoid!

TIP 2: Check the air gap of the new spark plugs with a spark plug gapper.

TIP 3: Use a torque wrench to tighten the spark plugs. If you don't tighten the spark plugs enough you run the risk of having them come out as you're driving down the road. This could also damage the spark plug hole threads in the cylinder heads.

If you over tighten the spark plugs, then you run the risk of damaging the threads of the spark plug hole.

The way to avoid any of these problems is to use a torque wrench to tighten the spark plugs.

More 1.7L Honda Civic Tutorials

You can find a complete list of 1.7L Honda Civic tutorials in this index:

Here's a small sample of the tutorials you'll find in the index:

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Honda Vehicles:

  • Civic DX 1.7L
    • 2001, 2002, 2003, 2004, 2005
  • Civic EX 1.7L
    • 2001, 2002, 2003, 2004, 2005
  • Civic LX 1.7L
    • 2001, 2002, 2003, 2004, 2005