So first off I'm pretty new to this forum, I actually think this is my first post.. But I have searched around on here AND on google and haven't really found anything specific to the problem I'm having. I bought a 2002 GS430 a couple weeks ago with 320XXX miles on it (ya i know) and for the most part everything was great. Car had a bad upper ball joint that I fixed, a cracked windshield and a CEL for the gascap which I fixed. After all that was done the car ran great for about 2 days which leads to where I am now.

A couple days ago I was getting onto the freeway, floored it to get past a semi, then the CEL came on and the car now feels like it has about half the power it should. Pulled the code and it was P0325. Left bank knock circuit or something like that. Reset it and the car ran great for another hundred miles or so then it came back on. Reset it again and it came on almost instantly. Seems to run ok just cruising down the freeway, maybe 4-5 mpg below what it was getting before but under any kind of acceleration its just pathetic now.

The previous owner only ever ran 89 octane in the car instead of 91-93 like whats recommended but to my knowledge the knock sensor never went off on him. I've ran about 4 tanks of 93 through the car and I'm stuck with this. So now I'm sitting with $450 worth in knock sensors, spark plugs and timing belt sitting in my rockauto cart and wanted to get some second opinions before I commit to ripping the top of the motor apart.

Are there any other reasons these cars throw that code? Am I actually knocking? could an injector be leaning out, running on 7 cylinders, bad MAF signal, etc? Thanks!

 

Check this thread;
https://www.clublexus.com/forums/gs-...325-cel-2.html

 

I forgot to say to you Welcome to the forum and club. Check this other youtube video.

 

Thanks, I think I skimmed through that one actually. Probably just gonna bite the bullet and do this whole ordeal. If anyone else has input its still welcome lol.

 

I had a knock sensor fail on my gs430 as well on around 110 tmls. changed it, since then no problems. also overhauled the starter motor.
if your timing belt is due, then change it. it is not really an advantage to do it with the knock sensor imho.

 

Think I'm gonna try to get everything knocked out Saturday. I've heard a full day for each job but I also have a friend who's a Toyota tech that says these jobs would take him about 5 hours in total.. Hoping I can get the timing belt and knock sensors finished in about 6-7 hours.

 

I have the same issue going on. I got the P0325 code for a knock sensor, and the car felt like it had 1/3 of its normal power. I replaced both knock sensors and a couple weeks later the problem is back. If I reset the computer it runs ok for a few days, especially if I stay out of the throttle. If I put it to the floor the code comes back much quicker. I'm also getting a P0420 code as well now. P0420 is a Catalytic converter code. Took it to the same shop that did the knock sensors and they are saying a blocked cat can cause the knock that would account for both codes. About had it with this damn car...

 

You can run the wire of you good knock sensor to both wires that go to your computer. Your code will be gone and your car will work perfect. The connector is right behind intake many fold so it's cramped in there. I've taken the intake off three times it's a 1.5 hour job by the time you've done it the third time. Make sure that the harness is good before u put it all back together cuz sometimes it's the harness and not the sensors

 

Lol. True that on the 3rd time. You get faster each time. Use OEM sensors.

 

I use oem sensors

 

Is there a good write up on pulling the intake somewhere? I found stuff for the timing belt but all the intake write ups I've seen aren't too helpful.

 

Read the threads on starter Replacement. Below are two good ones.
I would also use the opportunity to replace the contacts in your starter.
Good luck, and use caution with the knock sensor wire harness, it may be very brittle.

replaced-starter-this-weekend-not-as-bad-as-i-thought
1999 Lexus GS 400 Starting Problems

 

Thanks for the pics and info. I bought my sensors off rock auto.. the more expensive of the two options they had haha so hopefully they'll last. Replacing the plugs as well when I do this and then sending the injectors out to be serviced in a couple weeks. After I get all this done I don't see any reason why the thing wouldn't run great for another 100k

 

So yesterday I went to the hobby shop and got everything taken care of, new timing belt, water pump, idlers, spark plugs AND knock sensors. Fired the car up and after going through about 5 minutes of running like crap everything cleared up and the thing ran great. Idle seemed a bit cleaner and the car had a bit more torque below 2500 RPM (probably because the old plugs were toast). No check engine light to be found and I though "cool! everything's fixed".

Wrong. Went to go get dinner last night and as I was accelerating onto the freeway the CEL came back on and the car went back to being pathetically gutless. I'm assuming its the same code again, bank 1 knock sensor circuit.

When I took everything apart the harness was in good shape and I made a point to be careful when I was putting everything back together. I'm almost positive the car isn't knocking since all I run is 93 and before it throws the code it feels plenty healthy. Does anyone have an idea of what could be causing this code? I've only had the car for about 3 weeks now and I'm starting to think it was a waste of my money.

 

Please save yourself the trouble and go buy two new Toyota knock sensors from lexus. KNOWHERE ELSE!!! Install them and return your previously purchased ones. I've been down this exact road before. Bit the bullet and dropped 300 or something on the genuine Toyota sensors and never had a problem again.