datis250

Hi,

I am making this post because I could find similar results for other Lexus models, but not much for the 3IS or 2IS for that matter. I was driving my IS (3.5L 2GR FSE V6), when the check engine light came on, PCS light flashing, and trac off notification on my dash. The code I got was P0300. The car was driving fine, and no misfire was audibly detected or felt through the car. I cleared the code which was fine for a day. Then I got the dreaded flashing CEL the next day with a noticeable continuous misfire. Restarted the car at the side of the highway, and it went back to normal, no lights. Next day, driving on the highway and the CEL came on again (no audible misfires).

Here is what I noticed in my use case scenarios:

CEL, PCS, Trac off, P0300 - only activated when driving the car at 120kmh for 20m.
Flashing CEL - only activated when driving at 140 kmh for 20m, didn't check codes (not fully verified as this happened once, but logically it makes sense)
No codes/lights - under 115kmh

Car details: 2016 IS300 awd, 196,000km at time of misfires, never had plugs changed. Toyota calls for plugs at 190,000km.

Solution: 6 new spark plugs from Lexus.

Result: smoother idle, car feels more powerful, and returning better fuel economy. All of these things I noticed but didn't pay much mind too.

Cost for repairs: $200CAD, no labour costs since DIY. I could have gotten the plugs from RockAuto, as they carry denso which is the OEM, but $200 really isn't that bad and I didn't want to wait.

Thought I would share this for others, as this code can be a variety of things from my research. This was the solution for me, and while it has been a few days so far, I will update if this changes. All I can say is I pushed the hell out the car since doing the plugs and it should have misfired under those high load conditions, and so far it's running well.

Matroushi

Thanks for the write up and glad the problem is solved! Just one thing, I believe for the 2GR-FSE, the recommended interval for spark plug replacement is 100,000 km (60,000 mi), someone correct me if I'm wrong.

datis250

You are correct based on the service maintenance schedule that I pulled up online on Lexus.ca. My buddy has a friend at Toyota that checked on corporate's end and it stated 190,000km apparently. If we are being honest though, it's just a recommended item to prevent issues such as what I experienced. Seasoned mechanics will tell you not to change them at all until they go though. This was my experience with my dad, my friend, and interestingly Car Care Nut on Youtube!