Owners of other Hyundai, Genesis or Kia vehicles such as the Sonata, Accent, Veloster, Ioniq, Kona, Nexo, Venue, Tucson, Santa Fe, Palisade, G70, G80, G90, Soul, Sportage, Niro, Sorento, Telluride, Rio, Forte, Optima, Stinger, Cadenza, K900, Sedona and Seltos may also find these DIY instructions to be helpful.

The OEM (original equipment manufacturer) spark plug part number in this 2018 Elantra with the Nu MPI 2.0L Atkinson-cycle I4 engine were the Yura ELR9IQP9+ which are also known as part number Hyundai / Kia 18867-09095.

A few compatible replacement aftermarket spark plugs with their part numbers are as follows: NGK SILZKR7B11 (9723), Denso 3461, Bosch 9686, Champion RER8WMB (9409) and Autolite XP5702.

I cross referenced and verified the above part numbers at a variety of auto part manufacturer websites and auto parts store websites but as of right now the Amazon Part Finder site doesn't have any aftermarket spark plugs listed for the 2017, 2018 or 2019 Elantra.

The tools and other items needed to replace the spark plugs include a 10mm socket, a short extension bar, a 1/4" drive ratchet, a 5/8" spark plug socket, a long 3/8" drive extension bar, a 3/8" drive ratchet and a tube of dielectric grease.

The first two steps are to open the hood and then locate the silver metal bolt at the front left (passenger) side of the black plastic engine cover.

Remove the bolt by turning it in the counterclockwise direction with a 10mm socket and a 1/4" drive ratchet.

Set the engine cover bolt aside in a safe place.

Try to avoid using excessive force to prevent from cracking the cover.

Set the engine cover aside in a safe place.

If you have access to compressed air or a wet/dry shop vacuum, clean off the top of the engine to help reduce the risk of having dust or debris fall down into the spark plug well.

I also recommend only checking or changing one spark plug at a time to further reduce the chance of having a foreign object or debris fall down into the cylinder.

Gently slide back the grey plastic locking tab on the electrical connector.

Loosen the single bolt that secures the ignition coil housing to the top of the valve cover by turning it in the counterclockwise direction with a 10mm socket and a 1/4" drive ratchet.

Set the ignition coil bolt aside in a safe place.

Rotate the ignition coil back and forth a few times to make sure the rubber dust boot at the bottom of the coil isn't stuck or "frozen" to the top of the old spark plug.

Carefully pull the ignition coil straight out of the spark plug well and set it aside in a safe place.

If you need to replace any faulty ignition coils the OEM part number is Hyundai 27300-2E601.

Attach the 5/8" spark plug socket to the extension bar and a 3/8" drive ratchet.

I like to attach the spark plug socket to the extension bar with some blue painter's tape to make sure it doesn't pop and become stuck down in the spark plug well.

Loosen the old spark plug by turning the ratchet in the counterclockwise direction.

If you trouble loosening the old spark plug, try spraying a small amount of penetrating oil down into the well.

Allow the penetrating oil to seep into the threads and loosen any rust or corrosion for at least ten to fifteen minutes.

Once the old spark plug is loose, detach the ratchet from the extension bar and spin out the plug the rest of the way by hand.

Carefully lift the old spark plug out of the well.

Inspect the old spark plug for any signs of damage. If the old plug appears to be burnt or covered in soot or oily sludge, the engine might be burning oil and should be inspected by a professional mechanic.

If the electrode tip on the old plug appears to be burnt or covered in white powder, the engine might have been subjected to overheating. You may need to choose a spark plug with a different heat range for your climate or check your engine's cooling system.

I recommend buying the original OEM iridium tipped spark plugs which are part number Hyundai 18867-09095.

According to the service manual (or "shop manual"), the OEM Yura Tech ELR9IQP9+ spark plugs should be gapped to 0.8mm to 0.9mm or 0.0314" to 0.0354".

If you buy the NGK SILZKR7B11 (9723) spark plugs, the gap specification is .043" (1.1mm).

The gap specification for the Denso 3461 (SXU22HCR11S) is also .043" (1.1mm).

Don't be tempted to buy cheaper copper or platinum plugs since they have a much shorter lifespan than the iridium plugs.

If you have a spark plug gap gauge, check the gap on the new spark plugs. Iridium tipped spark plugs are pre-gapped from the factory and should not be adjusted.

If the new spark plug was dropped or damaged in shipping and the gap is incorrect, you will have to return or exchange it.

Push the new plug into the socket. Your socket should have a rubber insert or a strong magnet to hold the plug securely in place.

Carefully lower the new spark plug down into the well.

Spin in the new spark plug in the clockwise direction by hand until it makes contact with the cylinder head.

Attach the 5/8" drive ratchet and continue tightening the new spark plug to a small fraction of a turn past finger tight. You might feel the new crush washer collapse.

If you have a torque wrench, the service manual specification for the spark plugs is 11 to 18 lb-ft of torque.

Most spark plug manufacturers recommend that you do NOT use anti-seize lubricant since it can easily lead to over tightening.

If you are re-installing the old spark plugs after checking them, just tighten them to a small fraction of a turn past finger tight.

Double check that the new spark plug is tight before moving on to the next steps.

The dielectric grease will help ensure a reliable electrical connection by keeping out dust, moisture and debris.

Carefully lower the ignition coil down into the well and push it on to the top of the new spark plug.

Rotate the ignition coil back and forth a few times to help spread the dielectric grease.

Spin in the ignition coil bolt a few turns by hand in the clockwise direction to help prevent it from becoming cross threaded.

Try to avoid over tightening the bolt to prevent from cracking the plastic ignition coil housing.

Push the electrical connector straight on to the ignition coil's socket.

You should feel or hear the power plug "click" securely into place.

Slide the grey plastic locking tab straight in to secure the electrical connector.

Line up the grey rubber friction fasteners with the metal pegs or "spikes" on the top of the engine.

Push on the cover to secure the friction fasteners.

Replace the bolt on the front left corner of the engine cover by turning it in the clockwise direction with a 10mm socket and 1/4" drive ratchet until it is snug.

Start the engine and listen closely for any strange sounds that might indicate a problem such as a loose spark plug or a disconnected electrical connector.

If you do hear a strange noise, immediately turn off the ignition and double check your work.

The owner's manual service interval specification for the spark plugs is to change them every 97,500 miles.

Be sure to write down the spark plug change in your vehicle's service records.

For more, please check out all of my 2017-2020 Hyundai Elantra DIY Repair & Maintenance Guides.