Did the Check Engine Light on your car’s dashboard stay on long after you turned on the ignition switch?
Troubled, you put to use your trusted pal – the OBD II scanner. It returned something you’ve no clue about – the P0354 code!
Keep reading to get answers to these and more.
This Article Contains:
- What Is the P0354 Code?
- What Does the Code P0354 Mean?
- What Causes the P0354 Error Code?
- 5 Common Symptoms of Code P0354
- Is P0354 a Critical Code?
- How Is the Code P0354 Triggered?
- How to Diagnose and Fix Fault Code P0354?
- 4 FAQs About Your Car’s Ignition System
Let’s get started.
What Is the P0354 Code?
Code P0354 is defined as “Ignition Coil D Primary or Secondary Circuit Malfunction.”
It’s a generic Diagnostic Trouble Code (DTC), which implies that this code points to the same issue in all vehicles, irrespective of their make and model. However, the diagnosis and fixes for the error code could differ in that respect.
But what exactly is this fault code saying about your car?
What Does the Code P0354 Mean?
Code P0354 indicates that your Powertrain Control Module (PCM) or Engine Control Module (ECM) has detected an issue with the primary or secondary circuit in ignition coil ‘D’ — the coil used on cylinder number 4 (cyl #4) of your engine in a Coil on Plug (COP) ignition system.
Here, the last digit of this error code (‘4’) refers to the cylinder number where the problem has occurred.
Next, we’ll cover the possible reasons behind this trouble code.
What Causes the P0354 Error Code?
Problems with different components can commonly trigger the fault code P0354, including:
- A faulty ignition coil or ignition coil circuit
- Bad coil pack
- Short or open COP driver circuit
- Defective spark plug
- Leak in the intake manifold
- Idle air control valve malfunction
- Broken connector lock
- Blockage in air passages of the throttle body due to carbon build-up
- Loose connection at the ignition coil connector side or the ECM or PCM connector side
- Faulty PCM or ECM
Are there any signs to look out for?
5 Common Symptoms of Code P0354
Your car could be indirectly trying to warn you about a DTC P0354 if there’s:
- An illuminated Check Engine Light
- Sluggish acceleration
- Rough idling and vibrations while driving
- Power loss, especially under heavy engine load
- Difficulty starting the engine
Now, the question is – can you drive with the DTC P0354?
We’re at it!
Is P0354 a Critical Code?
In short, yes.
Remember, the P0354 DTC gets logged when proper ignition doesn’t occur in cylinder number 4. This can lead to the following consequences:
- The other cylinders in the engine must work harder to make up for the power lost due to improper ignition in cylinder 4.
- Your car’s engine will start to misfire intermittently, which can damage or clog the catalytic converter.
- You may experience drivability issues that can compromise your road safety.
If your car throws the P0354 trouble code or other related codes such as DTC P0353, P0351, etc., seek professional assistance ASAP.
You’re already familiar with the causes for code P0354. Let’s also find out what exactly takes place under the hood.
How Is the Code P0354 Triggered?
This error code comes up when the ECM or PCM doesn’t detect a voltage spike in the ignition coil D’s primary winding (primary coil). When the current to the primary coil from the battery is turned off, it generates a voltage spike in the primary and secondary windings. The spike in the secondary winding is much higher (up to 40kV) and is directed to the spark plug.
In some vehicles, the ECM shuts down the fuel injector for a given cylinder if it finds a problem with its ignition coil. E.g., the Toyota Motor Corporation uses an Ignition Confirmation Signal (IGF signal) to cut off the fuel supply to a cylinder in case of ignition failure.
Next, we’ll describe how a mechanic will determine the exact cause leading to the fault code P0354.
How to Diagnose and Fix Fault Code P0354?
To find out what caused the code P0354, a mechanic would:
- Take your vehicle for a test drive — if an engine misfire occurs, it indicates an issue with the ignition coil circuit.
- Perform a resistance test on the coil pack and see if there’s a wiring issue.
- Check if the coil pack wiring harness has a proper ground supply.
- Inspect the condition of the spark plug connected to the ignition coil.
- Look at the intake manifold for signs of a vacuum leak.
- Check if the ECM or PCM control circuit is working as expected.
- Examine the Hertz signal in the coil circuit to confirm that the ECM or PCM is sending the proper signal.
- Check the ECM or PCM connector and ignition coil connector for loose connections.
- Verify that there are no indications of fraying, corrosion, or melting on the wiring harness connecting the coil pack and your Engine Control Module or Powertrain Control Module.
To fix the DTC P0354, the mechanic may:
- Replace the defective ignition coil (or the coil driver circuit)
- Replace the bad coil pack
- Replace the damaged spark plug
- Repair the vacuum leak in the intake manifold
- Repair or replace the wiring harness between the coil pack and the ECM or PCM
- Restore or replace the malfunctioning PCM (or ECM)
Next, we’ll answer some common questions about the ignition system.
4 FAQs About Your Car’s Ignition System
Here are answers to four questions to help you better understand the ignition system:
1. What Is an Ignition Coil?
It transforms a low voltage (12 volts) from the battery into a high voltage pulse for the spark plug. An ignition coil has:
- A laminated iron core at its center
- A secondary winding of thin insulated copper wire around the core
- A primary coil (winding) of thicker copper wire around the secondary coil
The number of wire turns for the primary coil to the secondary are in a ratio of 1:100.
2. What Is a Coil Pack?
A coil pack is an electronically controlled set of ignition coils regulated by your car’s ECM or PCM. This component builds up electrical energy and then releases it via the spark plug cables in your vehicle’s ignition system.
3. What Is a Spark Plug?
A spark plug is a small device that produces an electric spark using the high voltage generated by the secondary wiring (secondary circuit) of the ignition coil. The spark created by it ignites the air-fuel mixture in your engine, resulting in combustion.
Moreover, the spark plug also functions as a heat exchanger by transferring the heat generated in the engine to the vehicle’s cooling system.
4. What Is a Coil on Plug Ignition System?
The COP system eliminates the need for a distributor or spark plug wire setup. Here, each cylinder has its own ignition coil mounted on top of the spark plug. The ignition system is divided into a primary circuit and a secondary circuit:
- Primary circuit: It consists of the battery, ignition switch, ignition module (ECM), and the primary coil.
- Secondary circuit: It consists of the secondary winding of the ignition coil and the spark plug.
The COP system can be classified into three arrangements:
- Two-wire: It doesn’t have an integrated switch and is controlled by the ECM
- Three-wire: The third wire provides commands from the ignition module to the coil’s switch
- Four-wire: It uses an additional wire to convey the IGF signal to the ECM.
The P0354 trouble code in an OBD II scanner indicates an ignition coil problem, resulting in an engine misfire and reduced performance. As there can be various reasons behind a DTC P0354, it’s important to have a qualified technician inspect your vehicle.
What about getting it done right there in your driveway?
Yes, that’s possible – with RepairSmith!
We’re a mobile auto repair service company that can diagnose and fix your DTCs without you having to risk a drive to the workshop.
Contact us for an easy online booking, and our expert mechanics will take care of your car’s error codes and other maintenance needs.