Owners of other Toyota and Lexus vehicles such as the Camry, C-HR, Venza, Avalon, 86, Sienna, Tacoma, RAV4, Highlander, 4Runner, Sequoia, IS 350, RX 350, UX 200, GS 350, IS 300 and ES 350 may also find these DIY instructions to be helpful.

The OEM (original equipment manufacturer) spark plug part number is Denso FC16HR-Q8 (also known as Toyota 90919-A1001 or Toyota 90919-01289).

A few aftermarket spark plugs that should be compatible with their part numbers are as follows: Autolite XP5684, Champion 9410 and Autolite AI5684.

(Note - If your Corolla has the M20A-FKS 2.0L I4 engine, the OEM part number is Denso FC20HR-Q8.)

The tools needed to complete the procedure include a 10mm socket with a 1/4" drive ratchet, a 14mm spark plug socket (or a 9/16" spark plug socket), a long extension bar, a 3/8" drive ratchet and a tube of dielectric grease.

The first two steps are to open the hood and locate the four ignition coils.

(If your vehicle is equipped with a plastic engine cover, carefully pull off the cover and set it aside in a safe place.)

To help reduce the risk of having a foreign object or any debris fall down into the spark plug well, clean off the top of the engine with compressed air of a wet/dry shop vacuum.

Push in the release button on the electrical connector.

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

Spin out the bolt the last few turns with your fingers to help prevent it from falling down and becoming lost in the engine bay.

Set the ignition coil bolt aside in a safe place.

You may need to hold up the flexible plastic cowl out of the way in order to remove the ignition coil.

Inspect the old ignition coil for any damage or wear.

If you see a CEL (check engine light) or SES (service engine soon) warning indicator on your car's gauge cluster, use an OBDII scanner (also known as an OBD2 scan tool) to check for an ignition coil related DTC (diagnostic trouble code) including P0350, P0351, P0352, P0353 and P0354.

If you need to replace a faulty ignition coil, the OEM part number is Toyota 90919-A2009 (also known as Denso 04C19-020105).

Set the ignition coil aside in a safe place.

Attach the 14mm spark plug socket to a long extension bar and a 3/8" drive ratchet.

(If necessary, you may also be able to use a 9/16" spark plug socket since 9/16" is about 14.2875mm.)

I like to use some painter's tape to secure the extension bar to the spark plug socket to make sure it doesn't pop off down at the bottom of the well.

Lower the socket over the old spark plug.

Carefully loosen the old plug by turning it in the counterclockwise direction.

If you have trouble loosening the old plug, try spraying a very small amount of penetrating oil down into the well. Just a few drops should be enough.

Allow the penetrating oil to seep into the threads and loosen any corrosion (rust) for at least 10 to 15 minutes.

Spin out the old plug the rest of the way by hand.

Lift the old plug out of the well and detach it from the socket.

Inspect the old spark plug for any soot, sludge or white ash.

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

If the old spark plugs are dark grey or covered in black soot, the engine might be burning oil and should be checked out by a professional mechanic.

If possible, I recommend that you buy the original spark plugs which are part number Denso FC16HR-Q8 (also known as Toyota 90919-A1001 or Toyota 90919-01289).

(Warning - Most spark plug manufacturers recommend that you do NOT use anti-seize lubricant grease on the threads of the new spark plugs since it can easily lead to over tightening.)

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

Lower the new spark plug down into the well and spin it in a few turns by hand in the clockwise direction to help prevent it from becoming cross threaded.

Tighten the new plug in the clockwise direction with the 3/8" drive ratchet until it is snug or about 1/8th to 1/4th of a turn past finger tight.

I don't have the service manual for the 2020 Corolla, but the torque specification for tightening the spark plugs in the shop manual for the 10th generation (2009, 2010, 2011, 2012 & 2013) Toyota Corolla with the 2ZR-FE 1.8L I4 engine is 15 lb-ft (or 20 Nm).

Note - I have never used a torque wrench to tighten spark plugs.

Avoid over tightening the spark plugs!

If you are just re-installing the old spark plugs after checking them, you may only need 1/8th of a turn past finger tight to properly tighten the old plugs.

Apply a thin layer of dielectric grease to the opening in the rubber dust boot at the bottom of the ignition coil.

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

Lower the ignition coil down into the well.

You may need to hold up the flexible black plastic cowl (located just in front of the windshield) in order for the ignition coil to be installed into the spark plug well.

Line up the bolt hole in the ignition coil with the corresponding bolt hole in the valve cover on the top of the engine.

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

(The Toyota shop manual specification for tightening the 10mm ignition coil bolts is 7 lb-ft or 10 N*m.)

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

If your car is equipped with a plastic engine cover, push it back down into place.

To test the new spark plugs, start the engine and listen closely for any strange sounds. If you do hear a weird noise, immediately turn off the ignition and double check your work.

Don't forget to write down the procedure in your vehicle's service records.

According to the service schedule in the "Warranty & Maintenance Guide", the OEM spark plugs should be changed after 120,000 miles or 144 months.

Please check out all of my 2020 Toyota Corolla DIY Repair & Maintenance Guides.