How to Replace Spark Plugs in Your Car

Engine Related Issues

By Rodney (Mechanics)

Table of Contents

Sparkplugs are core elements of your car’s engine working to spark the fuel-air mixture that indeed provides the power to drive your vehicle. On the other hand, however, spark plugs may wear out, get filthy, or fail to function properly, which will lead to your engine’s failure to function properly, fuel efficiency decline and increase in emissions. Therefore, make it a practice of changing the spark plugs as often as it is required to, following the manufacturer’s manual or service schedule interval.

Installing new spark plugs is something that can be reckoned with fear, mostly if you have no prior experience working on your car engine or if you cannot reach it well. However, we are the ones who will help you to trace each step, and illustrate the way to replace spark plugs in your car in a safe manner. You will necessitate some miniaturized equipment, a new pack of spark plugs, and some degree of tolerance. Let’s get started!

How to Replace Spark Plugs in Your Car

What You Will Need

Before you begin, make sure you have the following tools and materials ready:

  • A ratchet wrench with an extension bar and a spark plug socket. A spark plug socket is a certain type of socket which is rubber inserting to provide the grip and protection to the spark plug. You can often find a set of the spark plug sockets with a ratchet set or, alternatively, purchase them separately at any auto parts store.
  • One could use a spark plug gap gauge or a feeler gauge. They are instruments that measure the distance from the electrode electrodes, which is known as the spark plug gap. The gap is therefore critical in spark intensity and timing. You have to adjust the spacing so it matches best for your unit which you can find in the owner’s manual or a sticker under your hood.
  • A torque wrench. This is a device that determines how much tension a pilot screw holds. Although it is important to get the correct torque for your specific engine, you can find a torque specification in your owner’s manual or under the hood where there is a sticker with the information you need. The spark plug can Fail or the engine can be damage if it is tightened too much or too loosed.
  • Wiring brush and rag. They are of help in removing dirt that is mostly in the spark plug thread and spark plug well. These has the ability to cause problems in the engines.
  • Antiseize lubricant and dielectric grease. They are supplied only if desired, but it is advisable to have them to prevent corrosion plus to improve the performance of the spark plugs. Unlike any other thread lubricant, anti-seize compound is brushed over the spark plug threads before installation preventing them from seizing tightly. Dielectric grease is made up of a silicone-based grease that you would apply to the inside of the spark plug boot where the wires connect to the spark plug, in efforts to prevent water and dirt from entering through such areas and, hence causing misfires.

Apply Dielectric Grease

Replacing Spark Plugs

Having all the things you require, you should follow all the steps below to get your spark plugs replaced.

  1. To park your car on level ground, turn your engine off. Wait until the engine is entirely cool before reaching to the spark plugs and the surrounding parts, which can get really too hot. You need to make sure you don’t forget to turn off the engine while it’s hot in order to avoid injuring yourself or the engine.
  2. Pop the hood and find those spark plugs. Based on your engine type as well as its layout, the spark plugs can be at the top, left or right side or backward. Search for a collection of wires with a complete route down towards the engine where they will end up in the spark plug wells where the spark plugs sit. It is possible that you will be required to remove some bolt covers or others parts in order to get to the spark plugs. Keep in mind your owner’s manual or a repair guide that fits your car and engine and get more details.
  3. First put out the first spark plug wire. In case of any confusion, one spark plug must be modified at a time and be replaced in the same sequence they were installed. The first spark plug to work on should be the one that is closest to the front of the motor, then move your way back. Disconnect spark plug control wire by grabbing and twisting the boot so that it loosens. Then, get it out through the center and pull it up towards the spark cylinder. Please do not pull or jerk the wire itself as it may damage the wire or collapse the boot cable. If the boot is stuck or it gives much difficulty to be removed then you can use spark plug wire pliers to assist you. They are pliers with a specific contour and coating that enables it to pick up and protect the boot. In case of the boot or wire damages, the cable has to be replaced with a new one.
  4. Replace the old spark plug. Attach the spark plug socket to the extension bar and the ratchet wrench at the end. Slide the socket into the spark plug cavity while ensuring you push it over the spark plug. Using wrench, turn twisting clockwise and then remove it manually. Be aware that if you do inadvertently drop either the spark plug or the socket into the engine, you can cause some damage or you might find it hard to retrieve them. In case the spark plug is too tight or is cross-threaded, you can use some penetrating oil to help you unscrew it. First, sprinkle oil all around the spark plug, and let it saturate for a couple minutes before the next step. Do the same but this time, try to disconnect the spark plug. In case the spark plug is jammed, you may be required to apply force with the help of wrench or impact wrench. On the other hand, ensure that you are very cautious about the fact that you don’t brake the spark plug or twist the threads in a way which may lead to substantial issues. If this is your first time, or you are uncertain of the overall procedure, you may as well consider bringing a mechanic.
  5. Have a look at the spark plug. When you have taken away the old spark plug, you can view it to search for damage or signs of wear. The condition of the spark plug can be body language for the health of your engine and can reveal problems that are to come if any. Some spark plug conditions that help diagnose the problem:
  6. Normal: The spark plug has a shade of light tan /grayish. electrodes have worn down lightly. This is the signal that the spark plug is okay and the engine is well.
  7. Wet: The spark plug is dipping into oil, fuel or coolant. This, in turn, means no spark is generated by the plug and the engine is flooded, burned oil or leaks coolant. It can make the engine run improperly, misfiring or causing damages. To repair this issue, you will need to locate and patch the source of water leakage, and install a new plug for the spark.
  8. Carbon fouled: The spark plug is black and singed, and has got a coat of soot or carbon deposits. This shows that the spark plug does not fire and the fuel-air mixture doesn’t have enough air and is too rich. Such can beam a bad fuel injector, a clogged air filter, a faulty oxygen sensor, or a number of other issues. It will be all about you to check the fuel system and repair its if needed. But you also have to purchase the new spark plug.
  9. Oil fouled: The spark plug is very dark with oil or sludge. It is more black than anything else. This tells that the spark plug fails to fire thus the car burns oil. This type of issues is mostly sparked by rings, seals, and other parts of the motor. You have to complete engine checks and repairs, and add a new spark plug to the old system.
  10. Ash fouled: The spark plug is white and it’s surface looks like ash or metallic deposits build up on it. This shows a possibility that the spark plug is firing, but the oil or extraneous substances are being burnt instead. This can be induced through using low quality oil or fuel, or through a car’s catalytic converter or other emission system parts malfunctioning. You may need to replace and check the damaged parts, use the best quality motor oil and motor fuel.You may also need to replace the spark plug with a new one.
  11. Melted: The spark plug is white and blistered, and the electrodes are eroded or melted. This indicates that the spark plug is firing, but the engine is overheating or detonating. This can be caused by using the wrong spark plug type, a faulty ignition system, a lean fuel mixture, or other reasons. You will need to check and repair the cooling system, the ignition system, and the fuel system, and use the correct spark plug type. You will also need to replace the spark plug with a new one.
  12. Replace spark plug by Gap. However, before you install a new spark plug, make sure to gap it to the desired dimensions in accordance with your engine specification. The word ‘gap’ describes the width between the center electrode, which is the metal tip that sticks out of the spark plug, and the ground electrode, which is the metal arm that bends over the center electrode. The gap interests the rate of spark intensity and timing which are believed to be the main factors for engines’ performance and fuel-saving. Finding and rectifying the gap needs the use of the sparking plug gauge or feeler gauge. A plug gap gauge is a device that has a sequence of metal ridges or blades with each one marked with a measurement that represents a specific value. A Feeler gauge is a tool with more blades and precise measurements which is similar to feeler gauge. Use the tool and follow step below:
  13. Find your engine’s size on page 3 in the owners manual or look on the label under the hood. The differential is usually measured in thousandths of an inch and thereby written in 0.035 or 0.044.
  14. Choosing the right blade or wire that corresponds to the width of the gap you are trying to fill, you can also go with a set of blades or wires to achieve the accurate measurement. In other words, if the gap is 0.044, you can use a 0.040 blade and 0.004 blade, or a 004 wire.
  15. Slide the blade or wire between the spaced electrodes of the spark plug, and then inch it back and forth.It should fit.
  16. When a blade unwinds gradually or a wire goes through smoothly, without too much or too little resistance, that gap is correct. Further on, you will have to replace the ignition wire.
  17. If the blade or wire is just too loose or too tight, the gap is incorrect. You need to modify it through bending the ground electrode slightly, the use of the tool or your fingers. Do not bend the middle electrode, as it’s far fragile and can smash without problems. To growth the gap, bend the floor electrode away from the middle electrode. To lower the distance, bend the floor electrode closer to the middle electrode. Be cautious now not to bend it too much or too frequently, as this will weaken the metal and purpose it to crack. Check the gap once more with the blade or wire, and repeat the manner till you get the proper size.
  18. Change the old plug with a new spark plug. Before you install the new spark plug, you could consider applying some anti-seize compound as well as dielectric grease which prevents tarnishing and helps to improve the electric connection. To do this, follow all step below:
  19. Spread a thin film of anti-seize on the spark plug threads by your finger or a paintbrush. Do not excessive as this can lead to loss of can or may interfere with the spark. Avoid any appling to the electrodes, as it could worsen the spark quality and performance.
  20. Take a very little amount of dielectric grease, apply it inside the spark plug boot where the wire attaches to the spark plug. However, remember that applying too much glue may result in the boot slipping off or the spark plug failing to ignite. Do not try to apply this to the outside of the shoe because that might attract dirt and moisture.

Spark Plugs Gap

Steps for install the new spark plug

  • Plug in the spark plug to the spark plug hole, making sure it is fastened firmly. The rubber pad of the socket should attached the spark plug to it.
  • The spark plug hole is found on the cylinder head and the spark plug is positioned towards the threads by introducing the socket. Watch out that you’re not cross-threading or damaging the spark plugs or the engine. You can use a plastic tube or magnetics tool in order to lead the spark plug into the well when needed.
  • Turn spark plug with your hand clockwise until it is firmly tightened. Please avoid the ratchet wrench as you may put more force than needed and damage the spark plug.
  • Connect the torque wrench to the socket and set it to the desired torque for you engine. Such information will be in your manual or on a sticker on the hood. The torque value is displayed in foot-pounds or Newton-meters; 15 ft-lbs or 20 N-m for example.
  • Wind the torque key clockwise till the moment you hear a pop or feel a crack. This then informs you that you have reached the appropriate torque, and the spark plug has been fully tightened. Do not go beyond this point with the torque wrench because this could harm the spark plug or the engine.
  • Disconnect the torque wrench and socket from the spark plug hole.
  • Reconnect the spark plug wire. Follow instructions below to reconnect the spark plug wire.
  • At the wire of the spark plug that matches the spark plug you have just replaced locate it. There are wires that are more often than not marked or colored to be matched to each spark plug or traced from the distributor or the ignition coil should you not know the specific spark plug of your car.
  • Now grab the spark plug boot and begin to set it over the spark plug. Push till you feel a snap or hear a click. So it clearly means that a spark plug is tight and secured to the boot. Do not try to shove the jumper wire into the spark plug at any cost, as you might end up breaking the jumper wire or the spark plug. If the boot is too tight to push, you can use some dielectric grease for drinking inside of it.
  • Make sure the wire is routed correctly, and not touching any hot or moving parts of the engine. You can use wire clips or ties to secure the wire, if needed.
  • Follow the mentioned steps for every remaining spark plug. To get the job done, it will have to be repeated steps 3-8 for each and every spark plug, one at a time. Recall to turn the wires and use the exponents and torques in the correct orders. Do not confuse the coils, wires or the spark plugs as they can make the engine running unsteady or no at all.
  • Test the engine. After replacing all the spark plugs and reconnecting all wires, you may try the engine to see whether it runs smoothly and in the efficient state.. To do this, follow these steps:
  • Reinstall the use covers and the screws that you removed to get to the spark plugs. Ensure that everything is at the right place and has not slipped or shifted.
  • Turn engine on and let it idle for 5-10 seconds. Look at if there is any unusual noise or vibration, and check if there is any leak or smoke. Our budget will focus on developing student clubs, forums, and social events to build a sense of community among students. We will allocate 60% of the budget towards initiating these clubs, 30% towards organizing forums that discuss student concerns, and 10% towards social events that bring the student If your engine returns the “normal” sound and visual, then your new spark plugs are in place.
  • Say goodbye to your fumes, and instead take a short drive to analyze your vehicle’s recent performance. You must expect that with the help of this option the vehicle will accelerate faster and reach power earlier, fuel economy and emissions will improve. However, if you encounter any problems, like uneven idling, unwillingness to run, misfiring, check engine light on, you can be sure that you have wrongly installed the spark plugs or probably, there is another problem with your engine. Late next week, it would be good to verify spark plugs and resolve any unseen problems. In case the defect won’t stop you should go the expert auto mechanic.

Use Recommended Spark Plug on Manual


1. What kind of tool needed for replacing the spark plugs in my car?

  • To replace spark plugs in your car, you should have the necessary tools beforehand to avoid a frustrating and difficult process. First of all, your set will need to have a ratchet wrench with spark plugs socket adapters that come in various sizes in order to suit different spark plug types. Adding a socket extension may be needed to reach spark plugs that are positioned in small spaces and hidden deep within the engine bay. A spark plug gap tool is an important tool for setting up the gap between the electrodes of new plugs according to the manufacturer’s set specifications. At last, carrying a torque wrench along will assure that these spark plugs are turned to the designed torque specifications as against over tightening or under tightening.
  1. Spark plug socket attachments can be placed on ratchet wrench.
  2. Socket extension as well as something that will be going deep into the spark plug is there for you to use.
  3. A spark plug gap tool which metered the electrode gap to exact specifications.

2. Should I replace the spark plugs after every change of the oil or after every six months?

  • The number of spark plug replacement depends on multiple conditions, for example, whether the spark plugs are stock in your car or it is on the road. Mostly, with conventional copper spark plugs the time of replacement is somewhere between 20,000 to 30,000 miles, while platinum or iridium spark plugs are designed for longer period of usage, they have to be changed every 60,000 to 100,000 miles. Although, the manual must be governor for manufacturers advice about your particular vehicle brand and model.
  1. Replacement frequencies are tailored to specific spark plug type and driving conditions.
  2. Conventional copper plugs: 20 K – 30 K miles
  3. Platinum or iridium plugs: 60,000-100,000 miles

3. Can I do it myself by replacing spark plugs, or should I go to an expert?

  • Changing spark plugs is something that even the car owners with modest mechanical abilities and the relevant items can cope with. This is a pretty simple process where the old spark plugs would be accessed from the engine compartment, removed, replaced with new ones, and we shall make sure they are properly tightened. Nevertheless, if you are confused about your skills or you might not be equipped with the right tools then to consult the mechanic is essential to avoid any mishaps that can cause engine damage or reduce performance.
  1. DIY upgrade is easy to follow for individuals with mechanical skills.
  2. Necessary equipments and know-how should be provided enough for a professional replacement.
  3. Meet with an expert mechanic if the problem is too confusing or possibly lack of tools.

4. How do I determine when it is necessary to replace spark plugs?

  • They are mainly some symptoms to replace your spark plugs. One of the most common symptoms of a clogged catalytic converter is engine misfires, manifested as weakness, poor idling, or sluggish engine acceleration. If there is a drop in fuel economy or hard to start your car, use of faulty spark plugs could be the root cause. Furthermore looking into the spark plugs for signs of the electrodes erosion or excessive carbon accumulation burning away can give you a visual confirmation of replacement.
  1. Erratic engine backfires, poor idling, or unexpected “jamming” when accelerating.
  2. Increase in fuel consumption or delay in the starting.
  3. Visual inspection for indicators of damage like electrode corrosion or carbon deposit.

5. How do I go about replacing spark plugs in my car?

  • Replacing spark plugs involves a systematic action plan necessary for correct installation and maximum performance. To avoid the unintentional electrical discharge start by disconnecting the negative terminal of the car battery. Next, identify spark plugs in the engine bay and unplug the ignition coil or spark plug wires connected to each plug. Using a spark plug socket on the ratchet wrench, loosen and take away the old spark plugs. Install the new spark plugs with the help of a gap tool, gapping them according to the manufacturer’s specifications. Carefully and firmly put the new spark plugs into the engine cylinder head and tighten them to the prescribed torque with a torque wrench. Lastly, secure the ignition coil or spark plug wire back and hook the battery terminal.
  1. Remove the negative terminal of the car battery.
  2. Disconnect of ignition coil or spark plug wires.
  3. Replace old spark plugs with the right gap and torque settings.