2005-2015 Lexus IS250 Spark Plug Replacement | More info
DIY video demonstrating how to replace the spark plugs in your 2nd generation Lexus IS 250 with the 2.5 liter V6 engine. Replacing the spark plugs requires the disassembling of the upper intake manifold, air intake pipe and throttle body. This procedure will take approximately 1.5 hours to complete.
Spark plugs should always be replaced at approximately 100, 000 miles or sooner with OE quality long life double laser iridium plugs.
Spark plug brand recommendations are either Denso or NGK double laser iridium plugs.
Model years covered are 2005 - 2015.
Car in video is a 2008 Lexus IS250 AWD edition.
3/8" ratchet driver
1/4" ratchet driver
various socket extensions
5mm allen key socket (long and short length bits.
12 mm socket
12 mm wrench (stubby wrench is preferred)
10 mm socket
10 mm wrench
needle nose pliers
magnetic pickup tool
6 replacement spark plugs
nickel based anti-seize compound
flat blade screwdriver
replacement fuel line crush washers X2 (high recommended)
replacement throttle body o-ring (optional)
replacement intake manifold gaskets (optional)
Lexus IS: How to Replace Spark Plugs | More info
is the leading Lexus IS, ES, GS, and RX resource for technical DIY guides. Replacing the spark plugs on your Lexus IS is a do-able job, so long as you've got the right tools and follow these steps. For the full article, visit
A rough idle, misfires, and a sluggish throttle response are symptoms of a bad or dying spark plug. They're one of the few engine components that are exposed to combustion, so they're pretty rugged.
Still, Lexus recommends you change them every 60 thousand miles. However, they can fail earlier and trigger a check engine light.
Luckily, changing the plugs yourself isn't difficult.
This easy to moderately difficult job takes a few hours and costs around $90 dollars to complete. A professional will charge around $280 to replace spark plugs.
For this job, you’ll need new spark plugs, a 10 millimeter socket with extensions, a spark plug socket tool, a torque wrench, a flathead screwdriver, and a ratcheting or box wrench.
Step One - Remove engine covers and air intake assembly
Pop off the panels and remove the air intake assembly. You can see that the ignition coil is now easily exposed.
This image points to the ignition coil. Underneath it is a spark plug.
Step Two - Loosen the ignition coil harness
Using a small socket or wrench, loosen the 10 millimeter nuts holding the harness in place. This will provide wiggle room when pulling the coil packs.
Step Three - Remove the fastening nuts from the ignition coils and unclip coils
Now, fully remove the 10 millimeter nuts holding the ignition coils in place. Save the nuts and set aside on a magnetic tray or a cup.
Unclip the ignition coil from the wiring harness.
Step Four - Remove the old spark plug
The old spark plug will now be exposed.
Use the spark plug tool with an extension to remove the old plug.
Now that the spark plug is out, you can check its condition to see if your engine is having problems. A spark plug can tell you a lot about what's happening in your combustion chamber. Compare your plugs to ones on this chart.
Step Five - Install new spark plug
Using the spark plug tool and the extension, guide the new plug into the hole and thread loosely.
You can apply a small amount of motor oil to the threads of the new spark plug to avoid cross threading.
Step Six - Torque down the spark plug
Using the torque wrench, set it to 18 foot pounds and tighten.
Step Seven - Remove the ignition harness on the driver’s side
Navigate to the driver's side and remove the two nuts shown here. After they've been removed, lift the harness up and off to the side. Save and set the nuts aside.
Step Eight - Replace the spark plugs on the driver’s side
Repeat steps three to six on the driver's side of the engine. Don't forget to torque new plugs down.
Step Nine - Re-install nuts, the air intake assembly, and engine covers
Re-install the fastening nuts for the ignition coils and the harnesses.
Re-install the air intake assembly and engine covers when finished.