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Hyundai Tucson 2.4L Spark Plugs Replacement Guide
How to change the engine spark plugs in a 2nd generation 2010 to 2015 Hyundai Tucson with the Theta II 2.4L I4 motor.

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2014 Tucson 2.4L I4 Engine
Pull Off Plastic Engine Cover
4 Friction Fasteners
This automotive maintenance tutorial was specifically written to assist owners of the 2nd generation (2010, 2011, 2012, 2013, 2014 & 2015) Hyundai Tucson SUV in checking or changing the spark plugs in the Theta II 2.4L I4 engine.

Owners of other Hyundai and Kia vehicles equipped with the Theta II 2.4 liter inline four cylinder motor such as the Sonata, Santa Fe, Optima, Rondo, Cadenza, Sportage, Sorento and Forte may also find these DIY instructions to be helpful.

The iridium tipped spark plugs in this 2014 Tucson are Denso part number FXU16HR11 or "3478".

The OEM Hyundai iridium tipped spark plugs are part number 18845-11160 or 1884511160.

A few other compatible spark plugs with their part numbers are: Denso (4703) IKH16TT, Autolite XP6203 & ACDelco 41-800.

The tools and other items needed to complete this procedure include a 10mm socket with a 1/4" drive ratcheting wrench, a 5/8" spark plug socket, a 6" extension bar, a 3/8" drive ratchet, dielectric grease and an optional item is anti-seize lubricant.

Engine Cover Removed
Spark Plug Ignition Coil
Grey Plastic Locking Tab
The first two steps are to open the hood and then pull off the plastic engine cover.

Set the engine cover aside in a safe place.

Slide the grey plastic lock tab on the electrical connector away from the ignition coil to unlock it.

Pull Out Lock Tab
Push Down Release Tab
Pull Off Electrical Connector
Press down on the release tab and slide the power plug straight off the end of the ignition coil.
Loosen 10mm Bolt
10mm Bolt Removed
Rotate Ignition Coil
Loosen the single bolt holding the ignition coil in place to the top of the engine by rotating it counterclockwise with the 10mm socket and 1/4" drive ratcheting wrench.

Set the bolt aside in a safe place.

Rotate the ignition coil back and forth a few times to make sure that the rubber boot at the bottom of the coil is not stuck to the top of the old spark plug.

Pull Out Ignition Coil
Spark Plug In Well
5/8" Spark Plug Socket
Pull the ignition coil straight out of the spark plug well.

Attach a 5/8" spark plug socket to a 6 inch extension bar and a 3/8" drive ratcheting wrench.

Loosen Old Spark Plug
Detach Wrench - Spin Out
Pull Out Old Spark Plug
Lower the socket over the top of the old spark plug and loosen it in the counterclockwise direction.

If you can't loosen the old spark plug, do not use excessive force to avoid cracking the ceramic part of the plug.

Spray a small amount of penetrating oil such as PB Blaster, Liquid Wrench or Kano Kroil and wait at least 15 minutes or more before attempting to loosen it again. If you don't have any penetrating oil, try spraying some WD-40 or warm up the engine for a few minutes to help expand the metal engine block.

Once the spark plug is loose, detach the ratcheting wrench and spin it out by hand using the extension bar.

Lift the old spark plug out of the well and pull it out of the socket.


Denso # FXU16HR11
Lower In New Spark Plug
Spin In Clockwise
The OEM spark plugs in this 2014 Tucson are Denso part number FXU16HR11, which are also known as # 3478.

Inspect the old spark plug.

If the end of the old spark plug looks ashy white, the plugs may have been exposed to high temperatures such as overheating or they are the incorrect heat range for your driving conditions or environment.

On the other hand, if the old spark plugs are dark grey or covered in black soot, the engine may be burning oil and should be checked by a professional mechanic.

An optional step is to apply a tiny amount of anti-seize lubricant to the upper metal threads of the new spark plug. This will make the plugs easier to take out if they are not changed again for another 100k miles. Do not get any of the anti-seize on the electrode tip at the bottom of the new spark plug. Most spark plug manufacturers recommend that you not use anti-seize grease since it can lead to over tightening.

If you do apply anti-seize to the threads of the new spark plug, less force will be necessary to tighten them.

If you have a spark plug gap gauge, check that the gap on the new spark plugs matches the manufacturer's specification which should be .044". If a new spark plug's gap is not correct, it may have been dropped or damaged in shipment and should be returned or exchanged for a new one.

Push a new spark plug in to the socket and carefully lower it down in to the spark plug well.

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

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

Tighten With Wrench
Apply Dielectric Grease
Lower In Ignition Coil
Attach the ratcheting wrench to the extension bar and the spark plug socket.

If you are installing a new spark plug, continue tightening the plug in the clockwise direction until just barely past the point when you feel the crush washer collapse.

If you were just checking the existing plugs, tighten the old spark plug to just a small fraction of a turn past finger tight.

Try to avoid over tightening the spark plug to prevent from cracking the ceramic part of the plug.

Apply a small amount of dielectric grease to the opening of the rubber dust boot at the bottom of the ignition coil. The dielectric grease will help keep out any dust or moisture.

Gently lower the ignition coil down over the spark plug.

Spin In 10mm Bolt
Tighten 10mm Clockwise
Push On Electrical Connector
Spin in the 10mm bolt by hand in the clockwise direction.

Tighten the bolt by turning it clockwise with the 10mm socket and ratcheting wrench to just past hand tight.

Push the power plug straight on to the ignition coil until it clicks securely in top place.

Push In Grey Locking Tab
Replace Plastic Engine Cover
Spark Plugs Replaced
Push in the grey lock tab on the electrical connector.

Line up the four friction fasteners on the underside of the plastic engine cover and firmly push it back in to place.

Start the engine and listen for any strange sounds which may indicate a loose electrical connector or other problems.

For more, check out my other Hyundai Tucson DIY Repair & Maintenance Guides.

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