Navigating the Mystery of Ignition Coil D and Error P0354

So, your check engine light is giving you the stink eye with a P0354 code? If you’re behind the wheel of a Chevy Cavalier, Pontiac Sunfire, Toyota, Acura, or Pontiac Grand Am, this code means your Ignition Coil D Primary Secondary needs some attention. 

Specifically, it’s the ignition coil for cylinder #4 that’s acting up. Now, the big question on everyone’s mind is “Where is ignition coil D located?” Well, Ignition Coil D is usually perched on top of cylinder 4 – which is the middle cylinder on the bank closest to the front of your vehicle. 

However, if you’re still scratching your head trying to find it and how to get rid of that irritating code, we have got you covered. Rest assured that by examining the intricacies of this code, we will identify the potential origins, indications, and assessments to restore your vehicle to optimal condition. 

What Does the Error Code P0354 Mean?

Let’s first clarify what the error code P0354 actually means. According to the OBD II protocol, which has been unified for all automakers since 2000, we divide the electric system of automobiles into four basic units powertrain, body, and chassis network. 

This distribution is defined in the first character code. If the second character is expressed as zero, it is a standardized error. In the case of numbers one, two, and three, it is a more prestigious expression of the cast-specific error. 

So what does the diagnostic trouble code P0354 interpret specifically cure of car manufacturers? The basic definition is cylinder 4 ignition coil D primary or secondary circuit malfunction. With the engine running, the execution time is continuous, and the duration is 5 seconds or more. 

When the engine speed is 700 revolutions per minute, the return signal does not change for at least 5 seconds when the ignition coil is triggered. Here is the breakdown of the code “P0354”:

P- Powertrain

0- Standardized OBD II Number

3- Ignition System and Combustion Misfiring

54 – The specific issue; Ignition coil D primary or secondary circuit Malfunction (Cylinder #4)

Where is Ignition Coil D Located?

Where is Ignition Coil D Located?

Now, it’s time to discuss the ignition coil D location in detail so you can assess it independently. Where are the ignition coals, guys? In most modern vehicles,  Ignition coils are located on top of the valve covers above the cylinder. Most of the time, it’s made of plastic or aluminum. 

The ignition coil is connected with a wiring harness to the engine computer. And the engine computer will signal when the ignition coil is ready to send okay electricity to the spark plug. 

If you have three or four-cylinder engines, count three cylinders from the timing belt or chain. They usually have cylinder numbers one, two, and three. 

For a 4-cylinder engine, the next one will be four. If you have a V6 engine, things can be completely different. They can be done in two different ways. For instance, the Ignition curve, one, two, three, then four, five, six. 

Symptoms of Ignition Coil D Malfunction

The most obvious warning sign of malfunctioning ignition coil D is the error code P0354 shown on your dashboard. Like other malfunction codes, this code causes the Check Engine light to illuminate, drawing your attention easily. However, some additional indications are associated with drivability, such as:

  • Illuminated Check Engine Light
  • Engine hesitation while driving
  • Continuous or intermittent engine misfiring
  • Rough vibrations when driving or idling
  • There’s a loss or lack of engine power
  • Poor fuel economy and acceleration

Causes of the P0354 Error Code 

The error code P0354 is like a mystery novel with many suspects. Some of the possible culprits are discussed below:

Faulty Ignition Coils

If your ignition coil is acting up, you might just see that pesky P0354 code pop up. And let me tell you, a faulty coil can really mess with your ride. Typically, ignition coils are responsible for delivering the electrical current needed to create a spark in each cylinder of an engine. 

When an ignition coil fails or malfunctions, it can interrupt this process by preventing the spark from igniting properly. 

Your car might start misfiring, leading to some seriously scary situations – like your vehicle shutting down while cruising down the highway. Basically, if one of your cylinders isn’t firing right (or not firing at all), you’re in for an abnormal driving experience.

Vacuum Leak in the Manifold

If there is a vacuum leak in the manifold, it is probable that either the intake hose has broken or one of the numerous rubber tubes connected to the intake manifold has a break. These parts deteriorate and become fragile over time.

When a vacuum leak occurs, it reduces the amount of air entering the engine and causes a lean fuel mixture. This leads to several issues, including spark plug misfires and incomplete combustion. If left untreated for long periods, it can cause permanent damage to your car’s engine.

Thankfully, identifying the issue is not a complex task. To detect a vacuum leak in your car’s manifold, you should carefully inspect hoses and connections for signs of cracks and leaks. You should also consider using a smoke machine or propane torch to locate any leaks more efficiently.

Faulty Spark Plugs

At the root of this problem lies faulty spark plugs. Spark plugs provide an electrical charge that ignites the air/fuel mixture in your engine’s cylinders. If your spark plugs are worn out or damaged, they may not be able to ignite the fuel mixture properly. 

This can result in misfires and incomplete combustion, which can trigger error code P0354. Ignoring this issue could lead to further damage to other critical parts, such as catalytic converters or oxygen sensors, that will result in costly repairs. 

Broken Air Control Valves

A broken air control valve can lead to various engine problems, including an error code P0354. This code is specifically linked to the ignition coil circuit of a vehicle’s engine. When the air control valve is faulty, it can cause a misfire or erratic behavior in one or more cylinders of the engine.

The ignition coil circuit is responsible for supplying power to the spark plugs that ignite the fuel within each cylinder. A malfunctioning air control valve can cause a disruption in this process by allowing too much or too little air into the engine. 

As a result, one or more cylinders may not receive enough fuel and oxygen mixture for efficient combustion, leading to misfires. This will trigger an error code P0354 as it indicates that there is a problem with the primary/secondary circuit of ignition coil D.

How to Diagnose Ignition Coil D Malfunction Error Code

ECM checks the ignition coil operation every 10 seconds, and if signals indicate an open or short circuit, ECM will set a fault code, and the engine warning lamp will turn on. As you see, there is a specific fault code for each ignition coil. 

So considering the fault code, you have to perform the following diagnostic procedure for that ignition coil engine. Before doing anything, it is very important to review the ignition coil wiring diagram. Here is how to perform a diagnosis effectively


When you turn the ignition switch to the on position, a power supply will be provided on ignition coils via the main engine relay. So you must have battery voltage on that pin. There is also an ignition coil fuse to provide this power supply. 

Also, the ignition coil is controlled by PCM using the other wire, which is called the control line. PCM will activate the control line when the engine is running according to the engine firing order. So primary coil will be activated, and a magnetic field will be around the primary coil. 


As soon as PCM cuts the control line, the magnetic field and primary circuit will collapse, which will induce a high voltage and secondary coil that must be used in the spark plug to ignite the air-fuel mixture inside the cylinder. 

Before removing the ignition coils, you can check their waveform to see if they work correctly. Also, you can get some more information through the waveform. To have this waveform, you must be. An oscilloscope that you can use only. 


Get the waveform from the primary coil circuit, and one of the control lines is shown. Here you can see an explanation of an ignition coil waveform dwell. Time is when the control line is connected, and the primary coil creates a magnetic field. 

Peak voltage is the increased voltage on the primary coil after collapsing the magnetic field. And spark duration is the time that spark is happening. You can see a comparison between two cases of ignition coil waveforms. 

In the left case, the discharge voltage is too low, so a wide spark plug gap and lean air-fuel mixture could be the cause. The right case has a long spark duration that could be from a narrow spark plug gap or rich air-fuel mixture. 

This is a case study of the ignition coil waveform affected by a faulty spark plug. After checking the waveform, the first step is to disconnect the ignition coil connector. Turn the ignition switch to the on position and measure the supply voltage, which should be the battery voltage. 


If there is not any power on all ignition coils, check the ignition coil fuse, which is normally in the engine fuse box. Otherwise, check the wiring to see if the power supply is correct. To perform the next test, turn the ignition switch off, disconnect the battery negative terminal, and disconnect the PCM connectors. 

When both PCM and ignition coil connectors are disconnected, check the continuity between the power and control lines. There should not be any continuity in this case. If you see the continuity, you must check the wiring to find the short circuit. 


This section shows you how to test the continuity between the ignition coil power supply and control line. Now it’s time to check the short to ground in the control line. When both connectors are disconnected, check the continuity between the control line and the good ground. 

There should not be any continuity in this case otherwise control line is shorted to the ground for testing the open circuit on the control line. Now test how much resistance there is in the control line using a multimeter your measurement must be less than one ohm. 

If nothing is wrong with the wiring, remove the ignition coil and test the primary coil’s internal resistance. You should also test the secondary coil’s internal resistance.

Which Repairs are Necessary to Resolve the P0354 Code Issue?

The necessary repairs to address the P0354 code will vary depending on the underlying cause, as there are multiple factors that can trigger this issue. To remedy the diagnostic trouble code, a mechanic may opt to 

  • Replace a defective ignition coil or its driver circuit, 
  • Restore or replace a malfunctioning PCM or ECM, 
  • Repair a vacuum leak in the intake manifold, 
  • Replace a damaged spark plug, 
  • Repair or replace the wiring harness between the coil pack and the ECM or PCM. 

Final Words

Are you still thinking, “Where is Ignition Coil D located?” Hopefully not. As a driver, you may wonder what repairs can resolve the P0354 ignition coil D malfunction, a prevalent vehicle issue. When this error code is present, your car’s driving performance and control are compromised, making it difficult to accelerate when necessary and putting you and your passengers at risk of accidents. 

Experts in the automotive community highly recommend having your car inspected as soon as this code appears. Additionally, adhering to a regular maintenance schedule can significantly reduce the likelihood of damaging important car components.

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