Welcome to another in-depth look at common car problems that can stump even the most experienced drivers and car fans. Today, we will learn more about Diagnostic Trouble Codes (DTCs), focusing on the P0356 check engine light code, which tends to make our dashboard light up.
This trouble code is part of a set that can mean problems with the ignition system, specifically with the ignition coils. Ignition coils are crucial for your car’s engine to run smoothly, as they provide the necessary spark to ignite the air-fuel mixture in the combustion chamber. If any of these fail, it can cause the car to perform worse and increase its emissions.
In this article, we’ll explain what the P0356 code means, how to find the symptoms that go with it, what the most common causes are, and how to fix the problem in detail. This post will give you the information you need, whether you’re a do-it-yourself fanatic ready to start a new job or you just want to learn more about how your car works. Let’s start figuring out what the P0356 ignition coil circuit problem is and fixing it so that your car keeps running at its best.
How common is the P0356 code?
The P0356 code isn’t one of the most common diagnostic trouble codes. How often it shows up depends on the vehicle’s age, mileage, and degree of maintenance. Some parts of the ignition system, like the ignition coils, wear out over time and may stop working, which can cause this code to show up.
However, the chances of running into a P0356 can differ between makes and models. Usually, cars with higher miles or that haven’t been serviced regularly are more likely to have this problem.
Ignition Coil Operation: Simplified
An ignition coil works using a basic principle called electromagnetic induction, which allows it to transform a small amount of electrical voltage into a much larger amount needed to jump the spark plug gap. Here’s a simplified look at how it functions:
Think of the ignition coil as a sort of magic trick that your car performs to start and run the engine. When you turn the key, your car’s battery sends a low voltage to the ignition coil. This is like a whisper, but the spark plug must hear a shout.
Inside the ignition coil, there’s a primary coil wrapped around a secondary coil. The primary coil takes the whisper from the battery and creates a magnetic field around the secondary coil. When the time is right, the ignition system tells this magnetic field to collapse suddenly. This rapid magnetic field collapses around the secondary coil, turning the whisper into a shout and creating a high-voltage spike.
This high-voltage spike is so powerful that it travels down to the spark plug, where it jumps across a tiny gap, creating a spark. This spark is the trigger that ignites the air-fuel mixture in the engine’s cylinders, producing the combustion needed to power the engine. This seamless transformation of a whisper into a shout, through a process not unlike a magic trick, allows your car to bring you the performance you rely on every day.
Are you still interested in how ignition coils work? Our article about the basics of ignition coils covers that. Go check it out!
Understanding the P0356 Code
The P0356 code is a unique Diagnostic Trouble Code (DTC). This means something is wrong with the ignition coil “F” circuit, AKA cylinder #6. This code is part of a larger group of codes dealing with the ignition system, specifically problems with individual ignition coils.
If this code appears, there is an electrical problem in the ignition coil circuit. This could be because of bad connections, an ignition coil that isn’t working right, or a problem with the ignition coil’s control circuit. This can cause misfires and reduce the engine’s performance.
How P0356 code triggers?
Imagine driving along when suddenly your car’s engine starts to stutter. It doesn’t have the power and smoothness it usually has and feels like it’s suffering. The Powertrain Control Module (PCM), your car’s computer, always checks whether the engine’s electronics, like the ignition system, work as they should.
The PCM pays close attention to the electrical signals coming from each ignition coil while you drive to make sure they are firing properly and at the right time to get the most out of the engine. However, suppose something goes wrong with the ignition coil of cylinder #6, such as a faulty electrical connection, a defective ignition coil, or a breakdown in the wiring. In that case, the expected performance signal deviates from the norm.
The PCM notices this anomaly as it fails to receive the correct signal from the coil’s circuit. This difference sets off the trouble code P0356, which directly points to a problem with the ignition coil on cylinder #6. After that, the PCM lets you know something is wrong by turning on the check engine light on your panel. If you see this message, your car must be checked out to work at its best again.
What is the normal secondary circuit voltage in an ignition coil?
The normal secondary circuit voltage in an ignition coil typically ranges from 15,000 to 60,000 volts, depending on the coil design and the system requirements. This high voltage is necessary for the spark plug to generate a spark strong enough to ignite the air-fuel mixture in the engine’s combustion chamber. This high voltage ensures the engine runs efficiently by achieving complete combustion during each cycle.
Symptoms of P0356 Code
If you see the P0356 code, it means there are problems in the ignition coil circuit. These problems can appear in several ways and affect how well the car runs. If you notice these signs early, you can help avoid bigger problems later.
We will talk about the two main signs that your car might be having problems with the P0356 code in this section: the check engine light coming on and the engine misfiring. Knowing these signs not only helps you figure out what’s wrong but it also helps you fix it at the right time.
Check Engine Warning Light Illumination
The activation of the P0356 code typically manifests through the lighting up the check engine light on your vehicle’s dashboard. This indicator is a critical component of the onboard diagnostics system, serving as a universal alert for various potential malfunctions.
Using an OBD-II scanner, you can tackle the specific Diagnostic Trouble Codes (DTCs) causing the alert. The P0356 code may be identified as one of these codes, pointing to an issue that requires your attention.
Engine Misfire May Be Constant or Intermittent
Another significant symptom of the P0356 code is engine misfire, which can be constantly or intermittently present. Misfires feel like the engine is stuttering or hesitating, especially under load. This happens because the faulty ignition coil “F” cannot consistently provide the necessary spark, impacting engine performance and stability.
Can I drive with a P0356 code?
If you have a P0356 code, you shouldn’t drive. Keeping the car running with this code can damage the engine even more because of the misfires when the ignition coil isn’t working right.
In these conditions, driving can also greatly lower fuel efficiency and cause the engine to vibrate continuously, making the ride less comfortable and affecting the vehicle’s performance.
Causes of the P0356 Code
To make accurate diagnoses and effective fixes, you must know what causes the P0356 code to appear in your car’s diagnostic system. Several problems with the ignition coil circuit can cause this code to appear. Here, we will look at the most common reasons why the P0356 code might occur.
Defective Ignition Coil
A defective ignition coil is a common cause of the P0356 code. If the ignition coil fails, it cannot generate the high voltage needed to create a spark, leading to misfires and the activation of the check engine light.
Loose Connection at Coil or Broken Connector Locks
Loose connections at the ignition coil or broken connector locks can lead to intermittent or poor contact, which may result in the P0356 code. This physical disconnection or wear can disrupt the electrical continuity necessary for proper ignition coil function.
Short to Positive or Ground on Ignition Coil Driver Circuit
A short to positive or ground in the ignition coil driver circuit can disrupt the normal operation of the ignition system, causing the P0356 code. This condition interferes with the electrical signals that control the firing of the ignition coil.
Open Circuit on Ignition Coil Driver Circuit
Another potential cause of the P0356 code is an open circuit in the ignition coil driver circuit. This issue occurs when there is a break in the wiring, which prevents the ignition coil from receiving the necessary signals from the PCM.
Faulty Powertrain Control Module
Though less common, a faulty Powertrain Control Module (PCM) can also lead to the P0356 code. The PCM controls various aspects of the engine’s operation, including the ignition system. If the PCM malfunctions, it may incorrectly register a fault in the ignition coil circuit.
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Diagnosing the P0356 Code
Accurately diagnosing the P0356 code is crucial for effective repair and to ensure your vehicle runs smoothly. Here’s a step-by-step guide on how to pinpoint the issues leading to the P0356 code:
Retrieve Other DTCs
Begin the diagnostic process by checking for additional Diagnostic Trouble Codes (DTCs) stored in the system using an OBD-II scanner. It’s common to find multiple DTCs related to misfires, such as P0306, which can provide further clues about underlying engine issues. Want to know more about this DTC? Our detailed article about cylinder #6 misfire is a must-read!
Visual Inspection
Conduct a thorough visual inspection of the ignition coil and associated wiring. Look for loose connections, signs of corrosion, and any evidence of open or short circuits. If the P0356 code is intermittent, shake the wiring harness and ignition coil connector to see if the fault reappears, indicating a potential issue with the wiring or connection.
Perform a Power Balance Test
To further diagnose the problem, perform a power balance test by swapping the ignition coil in question (from cylinder #6) to another cylinder. This helps determine whether the misfire follows the coil to the new cylinder.
Check if the Fault Transfers
After swapping the ignition coils, if the misfire moves to the cylinder where the suspected faulty coil was placed, it confirms the ignition coil is defective. This step is crucial as it isolates the problem from the ignition coil rather than other components.
Measure Wiring Harness Resistance
If the misfire does not transfer with the ignition coil and remains at cylinder #6, measure the resistance in the wiring harness from the PCM and ground to the ignition coil. See if the wirings are also shorted to ground or positive. Look for any discrepancies and repair the wiring if defects are found. This step helps identify any electrical issues that aren’t immediately visible.
Defective PCM
In rare cases where all other diagnostics check out but the DTC persists, the problem might lie with the Powertrain Control Module (PCM). This scenario suggests a deeper issue within the vehicle’s computer system, which might require professional diagnostics and potentially replacing the PCM.
Fix the P0356 Code — DIY Ignition Coil Replacement
If you’re dealing with the P0356 code, it often indicates an issue with the ignition coil on cylinder #6. Replacing the ignition coil can usually resolve the problem, but it’s worth considering a comprehensive approach. Here’s a step-by-step guide to help replace the faulty ignition coil safely and effectively.
When one ignition coil fails, it’s generally a good idea to replace all of them simultaneously. Ignition coils tend to wear out at a similar rate, and replacing them altogether can prevent future misfires and related codes from occurring soon after. This approach ensures consistent ignition performance across all cylinders and minimizes the risk of similar issues recurring in other cylinders shortly.
Safety First
Before you begin, it’s crucial to prioritize safety:
Disconnect the Battery — Always disconnect the battery to prevent electrical shocks or unintended engine starts.
Wear Protective Gear — Use gloves and safety goggles to protect against accidental sparks or debris.
Cold to Touch — To prevent accidental burns, ensure the engine is cold to touch when working on it.
Tools Required
To replace the ignition coil, you will need the following tools:
- Safety goggles
- Working gloves
- Ratchet and socket set
- Spanner set
- Screwdriver set
- Ignition coil puller (if required)
- Spark plug socket
- Torque wrench
- Dielectric grease
Replacing Ignition Coils
Step 1 — Locate the ignition coils. In most vehicles, the ignition coils are easily visible once the engine cover is removed.
Step 2 — Carefully detach the electrical connector from the ignition coil. Check the connector for signs of wear or corrosion and clean it if necessary.
Step 3 — Use a socket wrench to remove the bolt securing the coil. Keep track of all screws and bolts.
Step 4 — Lift the old ignition coil out of the spark plug well. Inspect the area for debris or damage and ensure the spark plug boot is still attached to the ignition coil.
Step 5 — Place the new coil into the socket. Ensure it is seated properly when taken out.
Step 6 — Secure the new coil with the bolt and tighten it to the manufacturer’s specifications with a torque wrench.
Step 7 — Put a small amount of dielectric grease on the electrical connector to ensure a good connection and to prevent corrosion.
Step 8 — Reattach the electrical connector to the new coil.
Step 9 — Reconnect the battery and start the engine to test if the misfire and the check engine light are resolved.
Repairing Defective Wiring and Connections
To repair defective wiring and connections effectively, adhere to a meticulous repair strategy that ensures long-term reliability and safety. Begin by thoroughly inspecting the wiring for any visible damage, such as fraying or corrosion. Once the defective section is identified, cut out the damaged part cleanly. Use a wire stripper to prepare the ends for reconnection.
For a secure and durable connection, opt for one of two methods: using a butt connector or soldering. When using a butt connector, ensure it is properly crimped on both sides of the wire for a tight fit. If soldering, use heat shrink tubing over the soldered joints to insulate and protect them from environmental factors. Both methods restore the electrical system’s integrity while adhering to high repair standards if executed correctly.
Replacing PCM
Suppose the diagnostic process indicates a need to replace the Powertrain Control Module (PCM). In that case, ensure you have the correct replacement parts and tools to perform the job accurately.
Replacing the PCM involves precision and understanding of the vehicle’s electronic system, making this task challenging for many DIY enthusiasts. Due to the complexity and the need for precise programming and installation, many prefer to delegate this task to a professional.
This approach guarantees that the replacement is executed properly and helps avoid potential issues arising from incorrect installation.
Maintenance tips
Proper maintenance is crucial for extending the life of your vehicle and preventing issues like the P0356 code. Here are some essential tips to keep your ignition system and engine in top condition.
Follow Manufacturer Recommendations — Replace your spark plugs regularly according to the interval specified by the vehicle manufacturer. Worn spark plugs can lead to engine misfires, reduced fuel efficiency, and increased emissions.
Respond Promptly to Dashboard Alerts — Pay close attention to any warning lights on your dashboard, such as the check engine light or engine temperature warning light. These alerts are your vehicle’s way of telling you that something needs attention to prevent further damage.
Keep Your Engine Cool — Avoid conditions that lead to engine overheating. Excessive heat can damage “stick-type” ignition coils and other critical engine components. Ensure your cooling system is functioning correctly and that coolant levels are maintained.
Keep It Dry — Avoid cleaning your engine with a splash of water. Water can lead to electrical issues and corrosion within the engine compartment. If you must clean your engine, use methods that minimize water exposure, such as compressed air or specific engine cleaning products designed to protect electrical components.
Prevent Oil Contamination — Oil leaks, especially from a leaky valve cover gasket, can degrade the ignition coil and lead to misfires. Regularly inspect for oil leaks and address them promptly. Fixing oil leaks prevents ignition system issues and protects other engine parts from oil damage.
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