Hey guys! I just purchased a 2006 GS300 AWD w/115k. Started car on lunch hour to find check engine / check VSC lights on. Ran codes to find P0333 Knock Sensor code. Vehicle seem to run perfectly fine, but now that the light is on, it is definity spark knocking under acceleration. This is my first Lexus / Toyota product, so I am unfamiliar with the common problems or fixes. Hope someone can chime in! Are knock sensor replacements common? Thanks!!

 

What octane gas are you using? should be 91 or abaove

 

Using 91 octane. As I further diagnose this, I am finding that it is not only when the light is on that I am hearing what I believe was spark knock. I cleared the code, and it has not come back on, however, I am hearing the ticking sound when under load and driving. It is mostly heard with the window down, under acceleration. I do have the covers off the engine as I was looking for any signs some rodent may have tampered with wiring to the knock sensor, which may be increasing the volume. The sound is similar to a leaking manifold, except it doesn't seem to be affected by how warm the engine is (as far as I can tell). I tried a full throttle acceleration run last night and the car pulled very well with no hitches or signs of misfire. I hope to get it on a hoist this weekend so I can fully check the exhaust system for any signs of leaks. What baffles me is that if I load it up in drive with my foot on the brake (fully stopped), it doesn't seem to do it! Also, when I checked the local Lexus dealership for history on the vehicle, the advisor told me that it was in last June for a check engine light and they found that it needed a rear o2 sensor if the light came back on. I asked if it could be related, he said yes, but that doesn't sound right! An o2 sensor causing a knock sensor code? Sorry so long, but trying to get the info as I try to figure this out! Thanks again!

 

Sounds like you may have carbon buildup issues. Seems like the previous owner knew about it and maybe sold it off to you.

The 06's are notorious for carbon buildup. Excessive carbon will effect the o2 sensors. On the history records was the motor ever rebuilt? Lexus USA used to offer full rebuild/carbon cleaning to 06 owners. Another sign to look for is soot on the exhaust pipes.

If it was my car I would start off by removing throttle body and cleaning that. Then ide run 2 bottles of sea foam on a hot engine through the intake manifold vacuum line. Then finish it off with new oem spark plugs!

 

Thanks for the feedback! When I get it in the shop this weekend, I will do that! I will let you know how I make out! Thanks again!

 

Ticking noise could be the cat conv going bad and breaking up inside. If the code was a p0430 or p0420 from the dealership records and they already replaced o2s and they return with either one of those codes you have a bad cat.

 

I think you problem is the pig tail for the knock sensors, it under the intake manilfold. Slight ticking would not trigger the knock sensor.