How To Test The Nissan 1.8L COP Coils.

Testing the ignition coils (most commonly known as the COP ignition coils), on your 1.8L Nissan Sentra is pretty easy. You don't need any expensive diagnostic equipment to see if they have failed and causing the misfire code or condition your Nissan Sentra is currently experiencing.

In this tutorial, I'll show you how to test them in a detailed step-by-step fashion.

En Español You can find this tutorial in Spanish here: Cómo Probar Las Bobinas De Encendido (1.8L Nissan Sentra) (en:

Symptoms Of A Bad COP Ignition Coil

The Coil-On-Plug (COP) ignition coils are the ones that create and deliver the Spark that each engine cylinder needs to burn the air/fuel mixture.

When one COP ignition coil fails, that cylinder goes ‘dead’ due to a lack of Spark and is said to be misfiring.

The most obvious symptom of bad cop ignition coil, is a miss at idle and when you accelerate your Nissan down the road.

You're also gonna' see the check engine light (CEL) shining nice and bright on your instrument cluster and one (or several) of the following:

  1. Diagnostic Trouble Codes:
    1. P0300: Random Cylinder Misfire.
    2. P0301: Cylinder #1 Misfire.
    3. P0302: Cylinder #2 Misfire.
    4. P0303: Cylinder #3 Misfire.
    5. P0304: Cylinder #4 Misfire.
  2. Rough idle.
  3. Smell of raw gasoline coming out of the tailpipe.
  4. Bad gas mileage.
  5. Won't pass the emissions test.
  6. Extended cranking time (hard start).
  7. If more than one ignition coil is bad, your Nissan won't start.

If your vehicle is experiencing any of the above symptoms, chances are that you do have a bad COP Coil on your hands. Let's take a look at some of the basic tools you'll need to diagnose and repair this yourself.

What Tools Do I Need To Test The COP Coils

The most important tool that you're gonna' need, to test the ignition coils for spark, is a spark tester.

I'm gonna' recommend one that is the most effective (and the most inexpensive) out there: the HEI spark tester (KD Tools 2756).

From personal experience (I work full-time as an automotive tech), the HEI spark tester is a must have tool. You don't need to interpret the color of the spark or the weakness of it. With the HEI spark tester, if it sparks then you can conclude that the ignition coil is good.

  1. An HEI Spark Tester.
  2. Scan tool.
    1. A scan tool is not needed to check the COP coils with the info I'm presenting in this tutorial but it does come in handy to retrieve the misfire DTC (Diagnostic Trouble Code).
    2. Don't have one? Check out my recommendation: Abe's Scan Tool Recommendation.
  3. Wire piercing probe.
    1. Although this tool is not an absolute must, if you do buy one, you'll realize just how easy it makes testing the voltages inside the wires.
    2. If you need to see what this tool looks like, you can see it here: Wire Piercing Probe.

NOTE: You run the risk of damaging a good COP ignition coil by pulling the ignition coil off of the spark plug while the car is running (to listen for the audible clicking sound the spark makes). Also, this way of checking the COP ignition coil for spark doesn't produce an accurate test result. This is why a spark tester becomes a must have tool.

How Does The COP Coil Work?

Although it's not absolutely necessary to know how the Coil-On-Plug COP ignition coils work on your Nissan vehicle, I've included a brief description of how they work (for those of you who love to read the how and why of stuff).

In a nutshell, the COP ignition coil's job is to create and deliver spark to the spark plug.

Having an individual ignition coil per cylinder allows for a more maintenance free ignition system, since you have less moving parts that may wear out and that eventually need to be replaced like:

  1. A mechanical distributor assembly.
  2. Distributor cap.
  3. Distributor rotor.
  4. Spark plug wires.

Now, in case you're really curious about how it works, below is a very brief description of the whole process:

  1. When you turn the Key and crank the engine, power and Ground are supplied to 2 of the 3 wires sticking out of the COP ignition coil's electrical connector.
  2. The PCM (Powertrain Control Module = Fuel Injection Computer) gets the crankshaft position signal from the crank sensor.
  3. The PCM now activates each COP Ignition Coil.
    1. This activation signal (Triggering Signal) is supplied to the third remaining wire of the COP ignition coil's electrical connector.
    2. This Triggering signal activates an ignition module (also known as the power transistor) within the ignition coil
    3. The ignition module, in turn, starts to switch the ignition coil 12 Volts On and Off (by interrupting the coil's Ground circuit). Remember, all this is happening inside the ignition coil.
    4. It's the switching On and Off of the primary current (the fancy name for 12 Volts) that causes the COP coil to spark.
  4. With all 3 signals supplied (power, ground, and the triggering signal), the ignition coil now starts to spark.
  5. With fuel being injected, the engine in your Nissan comes to life.

OK, with this brief overview of how the COP ignition coil works on your 1.8L equipped Nissan, let's turn the page and get testing.

Where To Buy The COP Ignition Coils

You can buy the COP ignition coil at your local auto parts store or if you're like me and need to save money on any kind of purchase, you can buy it online.

You can check it out here:

2000-2001 Nissan Sentra 1.8L

2002-2006 Nissan Sentra 1.8L


Nissan Vehicles:

  • Sentra 1.8L
    • 2000,