2008 Toyota Highlander Hybrid Spark Plug Change Time Lapse

I finally tackled this project over the course of a weekend. The spark plugs were overdue for a change at 140,000 miles. The guides I found were for 2008+ conventional Highlanders with a 3.5L engine and 2007 and earlier Highlanders Hybrids but nothing for the 2008+ HiHy.

The original plan was to take the time to remove the plastic plenum and replace the plugs. The rear middle 12mm plenum support bolt was seized and would not come out. Unfortunately, I found this out after unscrewing the rest of the plenum. I remembered reading how others had not removed the plenum, so instead of fighting with the bolt I worked around the plenum. The extra room from loosening the plenum definitely helped but I think it would be tough for anyone who wears bigger than size medium gloves. The potential downside of loosening the plenum is not getting a good seal when reattaching the it.

The reason for the initial plan to remove the plenum was due to the brake master cylinder in the Hybrid which covers the open space on the passenger side of the plenum. This was difficult to maneuver around but moving a wiring loom definitely helped.

With the intake and plugs put back together, it was time to start it up. The car started rough and immediately started flashing Hybrid System Check, VSC Check and something else I couldn't catch. The check engine light was also on. I had forgot to reattach the rear middle wire harness to the ignition coil. Oops! You can see I pulled out a bore scope style camera to look behind the plenum.

The codes are cleared and everything runs well.

If you attempt to tackle this project, try without pulling the plenum and good luck!