Despite being relatively simple, spark plugs play a significant role in any gasoline engine. Their function is to produce a spark at the required time that ignites the air and fuel mixture. All spark plugs, being exposed to extreme pressures and temperatures that occur during engine operation, wear out with time. This can cause poor engine performance, misfire and drop in fuel economy. Also, a worn spark plug can have a larger electrode gap, which requires higher voltage and can lead to premature ignition coil failure.
While Porsche only recommends replacing the spark plugs as part of routine service, the ignition are known to go bad. Therefore, we also recommend replacing your ignition coils during every other spark plug change. This is a pretty straight forward DIY and a great way to save money. For an overview of the procedure, check out the video above from YouTube channel, CarFanatic. While the video covers the previous generation Cayenne, the process is nearly identical on the 958 hybrid models. You can find the parts, tools, and detailed instructions below.
- Mechanic’s Tool Set
- 3/8 Inch Drive Extension Set
- 3/8 Inch Drive Click Torque Wrench (10-80 ft.-lb.)
- 5/8 Inch Magnetic Spark Plug Socket
- 10-Piece Triple Square Socket Set, Metric 4mm – 18mm
- Torx Bit Socket and E-Torx Star Socket Set | 35-Piece
- Medium Strength Thread Locker
- Safety Glasses
- Disposable Gloves
Spark plugs: 22 ft-lbs
Engine strut torque mount bolts: 46 ft-lbs
Step 1: Prepare your vehicle and work area.
- Make sure your engine is cold; this is important so you prevent burning yourself and damaging your engine threads!
- Park your car on a flat surface.
- Gather required tools and parts.
- Put on gloves and eye protection.
Step 2: Remove the plastic panels surrounding the engine.
- Open the hood.
- As shown in the video from gtpiston04, remove the passenger and driver side plastic panels which are held on by plastic clips that you can remove with a flat head screwdriver.
Step 3: Remove the engine torque strut mount on the passenger side.
- You will see an engine torque strut mount (aka engine torque damper), which is held on with a 12mm triple square bolt and 16mm bolt.
- Remove the 12mm triple square bolt using the appropriate socket while holding the opposing nut in place with a 16mm socket.
- Then remove the final 16mm bolt.
- Note: Inspect the engine torque damper upon removal. If you see cracks, you’ll want to replace it with a new one, which can be found here on Amazon.
Step 4: Remove the passenger side ignition coils.
- Next on the passenger side, remove the plastic ignition coil cover which is held on by four T30 torx screws. Be careful not to drop these!
- With the ignition coils now revealed, carefully unclip the ignition coils.
- Use an E12 socket to remove the screws holding in the ignition coils; then, pull each ignition coil off.
- Inspect each ignition coil for cracks. While Porsche doesn’t recommend you replace the ignition coils as part of the recommended service schedule, these have been known to fail around 50-60k miles and sometimes even sooner.
Step 5: Replace the passenger side spark plugs.
- With the ignition coils off, you now have access to the spark plugs.
- So no debris falls into your engine, if you have a vacuum with a small nozzle, give each spark plug hole a nice clean.
- Use a magnetic spark plug socket and a 6″ extension to remove each spark plug.
- Without touching the electrode of the new spark plugs, carefully thread in each new spark plug by hand to avoid cross threading
- Torque each spark plug to 22 ft-lbs. DO NOT OVER TORQUE! If something doesn’t feel right, double check the calibration of your torque wrench.
Step 6: Re-install the ignition coils.
- Insert your ignition coils onto the spark plugs.
- Hand tighten the screws that hold the ignition coils in place.
- Re-connect the ignition coil wire harnesses.
- Re-install the plastic cover for the ignition coils and hand tighten the screws.
Step 7: Re-install the engine torque strut mount.
- Apply some medium strength thread locker to the 12mm triple square and 16mm bolts.
- Torque both bolts to 46 ft-lbs.
Step 8: Repeat the prior steps on the driver's side.
- You can repeat the prior steps on the driver’s side; however, you do not have an engine torque strut mount to remove.
- You will need to remove the engine air intake cover to give yourself enough room to access the ignition coils and spark plugs.
- Start by removing the 2 plastic pins that hold the air intake cover to the intake hose.
- Rotate the left pin clockwise and the right pin counterclockwise until they both line up with the visible notches; if you rotate the pins in the wrong direction, you will break them!
- Pull the plastic pins out with a set of pliers.
- Pop off the two clips on the air intake cover and remove the cover.
Step 9: Re-install everything.
- Start your engine to ensure it runs properly.
- Re-install the plastic engine panels.
- Clean up your work area and put your tools and supplies away.
- You’re all done!
