Hi guys, just purchased an 08 GS460, on a cold startup the engine idles a bit rough and throws a code for a knock sensor. As the car warms up you clear the code and it stays away. But the next cold start will throw the code again. I'm thinking defective knock sensor or dodgy rod bearings. My first step will be to bypass the knock sensor, and see if this stops the code. Does anyone have the ECU diagram for the gs460 I have looked around and can't find one. Would the ls460 ecu be the same? Thanks

 

I've seen someone on fb group had a similar issue and replaced the knock sensor.

 

First thing I would do is look at the spark plugs, if they are fouled. Who knows maybe the previous owner accidentally purchased fake plugs thinking they were original. Knock sensor code is coming on maybe because of knocking, not because the sensor itself is bad. A fouled plug can give a misfire and knock.

If you're hearing a hard metallic sound and you suspect its a connecting rod bearing. Pull the dip stick and examine the oil with a flash light, if theres a lot of shiny stuff then more likely something is not happy inside. But you really need a good scan tool to really diagnose this issue instead of slapping parts and money at it in hopes of finding a cure. A good scan tool can read what the knock sensor is reading, and if its bad it will show up right away. But if it isnt, also the tech can examine other parts of the engine. Do the easy stuff yourself like the plugs. Also another tip, log onto mylexus.com and run your vin number that will allow you to pull up the vehicle car history and see maybe the previous owner took it to the dealer and they diagnosed the issue.