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Acura MDX Spark Plugs Replacement Guide
How to check or change the spark plugs in a 1st generation 2001 to 2006 Acura MDX with the VTEC 3.5L V6 engine.

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2006 MDX 3.5L V6 Engine
Pry Off Bolt Cover
Left Rear Bolt Cap
This automotive maintenance tutorial was specifically created to assist owners of the first generation (2001, 2002, 2003, 2004, 2005 & 2006) Acura MDX in checking or changing the spark plugs and ignition coils on the J35A3 or J35A5 3.5 liter V6 VTEC engine.

Owners of other Acura or Honda vehicles such as the RDX, ILX, TLX, RLX, TL, CL, RSX, RL, TSX, ZDX, NSX, Integra, Pilot, Accord, Civic, Fit, Clarity, CR-V, CR-Z, HR-V, Odyssey, Element  and Ridgeline may also find these DIY instructions to be helpful.

The OEM spark plugs are the Denso SKJ16DR-M11 (3422) Iridium or NGK IZFR5K-11 (3657) Iridium.

The tools and other items needed to complete this procedure include a small plastic pry bar tool, a 10mm socket with a 1/4" drive ratchet, a 6mm hex socket or a 6mm Allen Key wrench, a 5/8" spark plug socket, a 3/8" extension bar set, a 3/8" drive ratchet and a tube of dielectric grease.


If your MDX has the check engine light (A.K.A. CEL, SES service engine soon) displayed and the engine error code (or DTC diagnostic trouble code) from the OBD2 port is P0351 or P0354, you may have a misfire due to a faulty ignition coil.

The OEM ignition coil part number is Denso 099700-072. A few other compatible replacement ignition coils with their part numbers are as follows: Denso 6732302, Delphi GN10168, Standard Motor Products UF400T and Wells C1221.

Right Rear Bolt Cap
Right Front Bolt Cap
Loosen Counterclockwise
The first two steps are to open the hood and locate the plastic manifold cover with "3.5 VTEC" written on it.

There are six round black plastic caps on the engine cover. The two caps in the center of the cover are decorative only and do not need to be removed.

Remove the four bolt caps at the corners of the engine cover by prying them out with a plastic pry bar tool or you can use a small flathead screwdriver.

Set the four bolt covers aside in a safe place.

Acura-MDX-Engine-Spark-Plugs-Replacement-Guide-007 Acura-MDX-Engine-Spark-Plugs-Replacement-Guide-008 Acura-MDX-Engine-Spark-Plugs-Replacement-Guide-009
Remove Four 10mm Bolts
Then remove the four bolts by turning them counterclockwise with a 10mm socket, an extension bar and a 1/4" drive ratchet.
Four Covers & Four Bolts
Lift Off Manifold Cover
Engine Cover Removed
Set the four bolts aside in a safe place.

Carefully pull off the engine cover and set it aside in a safe place.

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

Front Ignition Coils Cover
Black Plastic Fastener
1/4 Turn Counterclockwise
There is also a black plastic cover on the front edge of the motor that hides the front three ignition coils.

Rotate the two round black plastic fasteners 1/4 turn counterclockwise with a flathead screwdriver.

One of the fasteners is just above the orange oil dipstick handle and the other is just to the right of the oil filler cap.

Unlock Right Side Fastener
Lift Off Ignition Coil Cover
Front Three Ignition Coils
Pull the small black rubber hose off the top right side of the cover.

Pull off the ignition coils cover and set it aside in a safe place.

Once the cover is out of the way, you'll be able to see the three front ignition coils.

Rear Three Ignition Coils
Front Left Ignition Coil
Push In Release Tab
The three ignition coils on the rear of the engine are easily visible and accessible without removing any other items.

I recommend only checking or changing one spark plug at a time to help further reduce the risk of having debris fall down into the spark plug hole.

This tutorial will begin with replacing the front left spark plug located near the orange plastic oil level dipstick.

Gently push in the release button on the right side of the electrical connector.

Disconnect Power Plug
Loosen Counterclockwise
Spin Out Bolt
Pull the power plug straight off the ignition coil housing.

Use a 6mm hex head socket or a 6mm Allen Key wrench to loosen the bolt on the left side of the ignition coil.

Spin out the bolt the rest of the way by hand and set it aside in a safe place.

Ignition Coil Bolt Removed
Rotate Ignition Coil
Pull Out Ignition Coil
Gently rotate the ignition coil back and forth a few times to make sure that the rubber dust boot at the end of the ignition coil is not stuck or "frozen" to the top of the old spark plug.

Carefully pull the ignition coil straight out of the cylinder head.

Set the ignition coil aside in a safe place.

If your OBD II scanner indicates that one of your cylinders has a misfire, you may want to try replacing the ignition coil to resolve the problem. I recommend buying the Denso 6732302 ignition coil since it has excellent reviews on Amazon.

Insert Spark Plug Socket
Loosen Counterclockwise
Lift Out Old Spark Plug
Attach the 5/8" spark plug socket to the extension bar and lower it into the spark plug well.

Push the 5/8" spark plug socket on to the top of the old spark plug.

Attach the 3/8" drive ratchet to the end of the extension bar.

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

If you have trouble removing the old spark plug, do not use excessive force to prevent from cracking the old spark plug. You can try spraying in a very small amount of penetrating oil such as PB Blaster, Liquid Wrench or WD40 into the spark plug well.

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

Carefully lift the old spark plug out of the well.


Inspect Old Spark Plug
Spark Plug Well
Spin In New Spark Plug
Pull the old spark plug out of the socket.

Inspect both ends of the old spark plug socket for signs of discoloration or soot buildup.

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

If the electrode tip of the old spark plug looks grey or is covered in dark black soot, the engine might be burning oil and should be inspected by a professional mechanic.

The OEM spark plugs in this 2006 MDX were the Denso SKJ16DR-M11 Iridium.

Push the new spark plug into the socket attached to the extension bar and carefully lower it down into the well.

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

Tighten Clockwise
Apply Dielectric Grease
Re-Insert Ignition Coil
Attach the ratchet to the extension bar and tighten it in the clockwise direction.

If you would like to use a torque wrench, the service manual torque specification for the spark plugs is 13 lb-ft.

If you are re-installing an old spark plug, just tighten it to a small fraction of a turn past finger tight.

If you are installing a new spark plug, continue tightening the spark plug until you feel the new crush washer collapse.

Try to avoid over tightening the new spark plugs to prevent from cracking the plug or damaging the threads.

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

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

The dielectric grease will help keep out any moisture, dust or debris to ensure a reliable electrical connection. It will also prevent the rubber dust boot from becoming stuck to the top of the spark plug.

Lower the ignition coil into the spark plug well. Rotate it back and forth a few times to help spread around the dielectric grease.

Spin In Bolt Clockwise
Tighten Bolt Clockwise
Push On Power Plug
Line up the bolt hole in the ignition coil with the hole in the engine.

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

Tighten the ignition coil bolt by turning it clockwise with the 6mm hex head socket or Allen key until it is snug.

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 until it clicks securely into place.

Rear Left Ignition Coil
Electrical Connector
Loosen Counterclockwise
I'm glad that the Acura / Honda engineers left plenty of room in the rear of the engine bay. The rear three ignition coils and spark plugs are relatively easy to access compared to many other V6 engines.
Spin Out Hex Head Bolt
6mm Hex Bolt Removed
Pull Out Ignition Coil
Repeat the process to check or change the other spark plugs.
Rear Ignition Coil Removed
Loosen Counterclockwise
Spin Out Old Spark Plug
Lift Out Old Spark Plug
Inspect Old Spark Plug
Lower In New Spark Plug
Tighten Clockwise
Apply Dielectric Grease
Push In Ignition Coil
Spin In Clockwise
Tighten Ignition Coil Bolt
Push On Power Plug
Replace Ignition Coil Cover
1/4 Turn Clockwise - Lock
Secure Cover Fasteners
Lower the black plastic ignition coil cover back into place at the front of the engine bay.

Push the two fasteners back into their holes on the mounting bracket.

Rotate the two fasteners 1/4 turn in the clockwise direction with a flathead screwdriver to secure them in place.

Replace Rubber Hose
Replace Manifold Cover
Spin In 10mm Bolts
Push the black rubber hose back on to the right (driver) side of the ignition coils cover.

Lower the plastic cover back into place over the engine.

Line up the bolt holes in the cover with their corresponding holes in the manifold cover.

Spin in the four 10mm bolts a few turns in the clockwise direction by hand to prevent them from becoming cross threaded.

Tighten Bolts Clockwise
Pop In Bolt Caps
Spark Plugs Replaced
Tighten the four bolts in the clockwise direction with the 10mm socket and a 1/4" drive ratchet until they are snug.

Try to avoid over tightening the bolts to prevent from cracking the plastic cover.

Start the engine and listen closely for any strange sounds or noises that might indicate a problem such as a loose spark plug or a disconnected ignition coil power plug.

For more, please check out all of my 2001-2006 Acura MDX DIY Repair & Maintenance Guides.

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