How To Test The Ignition Coils (2000-2006 1.8L Nissan Sentra)

How To Test The Ignition Coils (2000, 2001, 2002, 2003, 2004, 2005, 2006 1.8L Nissan Sentra)

Testing the ignition coils (most commonly known as COP coils) on your 1.8L Nissan Sentra is fairly easy.

You don't need expensive diagnostic equipment to determine if these have failed and are causing the misfire code or rough idle problem your Nissan Sentra is currently exhibiting.

In this tutorial, I'll show you step by step how to test them.

In Spanish You can find this tutorial in Spanish here: Cómo Probar Las Bobinas De Encendido (2000-2006 1.8L Nissan Sentra) (at:

APPLIES TO: This tutorial applies to the following vehicles:

  • 1.8L Nissan Sentra: 2000, 2001, 2002, 2003, 2004, 2005, 2006.

Symptoms Of A Bad COP Ignition Coil

The coil-on-plug (COP) ignition coils create and deliver the spark that each engine cylinder needs to burn the air-fuel mixture it contains.

If a COP ignition coil fails, that cylinder will go 'dead' with no spark and a misfire will occur.

The most obvious symptom of a bad ignition coil is an engine miss when idling and when you accelerate your Nissan on the road.

You'll also see the Check Engine Light (CEL) shining nice and bright on your instrument cluster and one (or more) of the following diagnostic trouble codes:

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

You'll also see one or more of the following symptoms:

  1. Rough idle.
  2. Smell of raw gasoline coming out of the tailpipe.
  3. Bad gas mileage.
  4. Won't pass the emissions test.
  5. Extended cranking time (hard start).
  6. If more than one ignition coil is bad, your Nissan won't start.

If your Nissan Sentra is exhibiting any of the above symptoms, chances are you have a bad ignition coil on your hands. Let's take a look at some of the basic tools you'll need to diagnose and fix this yourself.

What Tools Do I Need To Test The COP Coils

The most important tool that you'll need to see if the ignition coils are sparking is a spark tester.

I'll recommend one that is the most effective (and cheapest) out there: the HEI Spark Tester (KD Tools 2756).

From personal experience (I work full-time as an automotive technician), the HEI Spark Tester is a must-have tool. You don't have to interpret the spark's color or its weakness.

With the HEI Spark Tester, you can conclude that the ignition coil is good if it sparks.

  1. An HEI Spark Tester.
  2. Scan tool.
    • A scan tool is not needed to check the ignition coils with the info I'm presenting in this tutorial but it does come in handy to retrieve the misfire DTC (Diagnostic Trouble Code).
    • Don't have one? Check out my recommendation: Abe's Scan Tool Recommendation.
  3. Wire piercing probe.
    • 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.
    • 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 ignition coil by pulling the coil off the spark plug while the car is running (to listen for the audible clicking sound the spark makes).

Also, this way of checking the ignition coil for spark will not give an accurate test result. This is why a spark tester becomes an indispensable tool.

How Does The COP Coil Work?

While it's not essential to know how the coil-on-plug COP ignition coils work on your Nissan Sentra, I've included a brief description of how they work (for those of you who would like to know the how and why).

In a nutshell, the role of the COP ignition coil is to create and deliver spark to the spark plug.

Having a single ignition coil per cylinder allows for a maintenance free ignition system as you have fewer moving parts to wear out that eventually need to be replaced such as:

  • A mechanical distributor assembly.
  • A distributor cap.
  • A distributor rotor.
  • The spark plug wires.

Now if you are really curious 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 applied to two of the three wires sticking out from the COP ignition coil electrical connector.
  2. The PCM (Powertrain Control Module = Fuel Injection Computer) receives the crankshaft position (CKP) signal from the CKP sensor.
  3. The PCM now activates each ignition coil.
    • This activation signal (trigger signal) is fed to the third remaining wire of the electrical connector of the ignition coil.
    • This trigger signal activates an ignition module (also called a power transistor) inside the ignition coil
    • The ignition module, in turn, begins cycling the 12 Volts to the ignition coil ON and OFF (by interrupting the coil's ground circuit). Remember that all of this happens inside the ignition coil.
    • It's the switching ON and OFF of the primary current (the fancy name for 12 volts) that makes the ignition coil spark.
  4. With all three signals present (current, Ground and the trigger signal), the ignition coil now begins to spark.
  5. When fuel is 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 Nissan Sentra, let's start testing them.

Where To Buy The COP Ignition Coils

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

2000-2001 Nissan Sentra 1.8L:

2002-2006 Nissan Sentra 1.8L:

Nissan Vehicles:

  • Sentra 1.8L
    • 2000,