Coil-on-Plug (COP) Coil Test (2002-2006 2.5L Nissan Altima, Sentra)

Testing and troubleshooting the ignition coils on your Nissan Altima or Sentra is not hard! This article will take you through the whole testing process step by step. You'll be able to easily diagnose a misfire condition on your Altima and/or solve a misfire code that may be lighting up the check engine light on your Altima or Sentra's instrument cluster.

Every step is explained in plain English and with photos to guide you every step of the way. Also, all tests are on-car tests and done without a scan tool. To find out if this info applies to your Altima or Sentra, check out the list of Nissan Altima and Sentra years at the bottom of this page.

APPLIES TO: This tutorial applies to the following vehicles:

• Nissan Altima 2.5L: 2002, 2003, 2004, 2005, 2006.
• Nissan Sentra 2.5L: 2002, 2003, 2004, 2005, 2006.

Symptoms Of A Bad Ignition Coil

Beside the check engine light annoying you, your Altima or Sentra may also experience one or several of the following symptoms:

1. Misfire codes that light up the check engine light (CEL) on your instrument cluster.
   • P0300, P0301, P0302, P0303, P0304.
2. Engine misfire that DOES NOT light up the check engine light (CEL).
3. Smell of unburned gasoline coming out of the tailpipe.
4. Rotten egg smell coming out of the tailpipe. This is due to the unburned gasoline from the misfiring cylinder over loading the catalytic converter.
5. Really bad gas mileage.
6. Lack of power as you accelerate the vehicle down the road.

What Tools Do I Need?

To test the Coil-On-Plug (COP) ignition coils you don't need an automotive diagnostic scan tool (commonly known as a scanner or scan tool). You do need a few basic tools and these tools won't break the bank.

1. An HEI spark tester
   • This inexpensive spark tester is a MUST have tool to be able to correctly diagnose the Coil-On-Plug ignition coils on your GM vehicle with the info and tests in this article.
   Don't use a regular spark plug instead of a spark tester.
2. Battery jump start cables.
3. A digital multimeter.
4. A helper.
   • You'll need someone to help you crank the engine while you perform the tests in the engine compartment.
5. A repair manual.
   • For whatever remove and replace info you'll need that is not covered by this article.

Circuit Descriptions: Nissan Ignition Coil Connector

The Nissan Altima/Sentra's ignition coil is a three wire Coil-On-Plug ignition coil.

Which means that each ignition coil has a transistor inside that plays the role of an ignition control module (ICM). Below are the circuit descriptions of each wire (circuit):

• Circuit labeled 1:
  • Power (12 V) Circuit.
• Circuit labeled 2:
  • Ground Circuit.
• Circuit labeled 3:
  • Triggering Signal Circuit.

You don't have to worry about the color of the wires as long as you're able to identify the circuit using the photos in each test step.

Do's and Don'ts And Precautions

The tests that you're about to learn/do in this article are very easy and simple to do. Some of them have to be performed with the engine cranking, so you still have to be on your toes and remain alert. Use common sense and take all necessary safety precautions. Here are some more suggestions:

1. Do not use a regular spark plug instead of a spark tester to test for spark.
2. Do not remove the ignition coil from the spark plug while the engine is cranking to test for spark. This method for testing for spark can ruin the ignition coil, and now you have another problem to worry about.
3. Start your diagnostic from TEST 1, do not skip around from test to test unless instructed to do so by the TEST you are currently on.
4. Once again, use the recommended/indicated tools for all of your tests.

Where To Buy The Ignition COP Coil And Save

The following links will help you to comparison shop for the ignition coil and hopefully save you a few bucks:

NOTE: Not sure if the ignition coil fits your particular vehicle? Don't worry. Once you get to the site they'll ask you for the particulars of your vehicle and they'll check it fits. If it doesn't fit, they'll find you the right one.

TEST 1: Testing For Spark

The spark test is the starting point of your troubleshooting on your Nissan Altima or Sentra. It's important to remember that you need to use a spark tester. For the most accurate spark test result I recommend that you use an HEI spark tester.

Whether you have a specific misfire code and you know which ignition coil you need to test or you don't know where to start testing for spark, I suggest you test all four ignition coils.

OK, now to get this show on the road:

1. 1

   Remove the ignition coil from the engine's valve cover.

2. 2

   Attach the HEI spark tester to the coil-On-Plug ignition coil (as shown in the photo above).

3. 3

   Ground the HEI spark tester using a battery jump start to a good Ground point on the engine or directly on the battery negative (-) terminal.

4. 4

   Have your helper crank the engine while you observe the spark tester.

5. 5

   The spark tester should spark.
   
   After noticing the result, which will be either spark or no spark, disconnect the spark tester and put the ignition coil back in place.

6. 6

   Repeat the test for all of the remaining Coil-On-Plug ignition coils on your Nissan Altima or Sentra.

Let's interpret your test results:

CASE 1: The spark tester sparked. This test result tells you that the ignition coil is fine.

Since your Altima (or Sentra) is suffering a cylinder misfire, take a look at the suggestions found here: TEST 6: Carbon Tracks And Other Stuff.

CASE 2: The spark tester DID NOT spark. In about 90% of the time, this test result lets you know that the ignition coil is fried and that replacing it will solve the misfire condition.

But, just to make sure that no other issues exists to cause this no-spark result on this ignition coil, the next step is to make sure that this particular ignition coil is getting power. For this test go to: TEST 2: Testing The Power Circuit (12 Volts).