MamiLS430

My LS430 recently had a few lights pop up on my dash....."check VSC and traction off lights" came on one morning. Found out that it is a knock sensor.

Can anyone elaborate on what a knock sensor is and can this cause more problems down the road? I haven't had the car all that long and it has put a sour taste in my mouth. I just got rid of a pain in the butt Cadillac and was told that a Lexus was the way to go. Hmmmmm!

Johnny

A knock sensor allows the engine to run with the ignition timing as far advanced as possible - which results in maximum power output. The ECU will continue to advance the timing until the knock sensor detects pinging (or knock). At that point the ECU retards the ignition timing just enough for the pinging to stop. In other words, a knock sensor assures that you're getting as much power and fuel economy as is possible from your engine.

MamiLS430

What is the thought on replacing both of the knock sensors if the second one is not showing that it is faulty? I suppose I should have asked that of the repair shop, but did not.

Is there a chance that the other one will follow suit or go bad in short time. I'm just hoping that it isn't the beginning of one thing after another.

Lastly, does this fall under the 70,000 power train warranty? Thanks in advance.

GeorgeT

It should fall under the 70,000 mile warrantee but they will probably just replace the bad unit. I wouldn't worry about the other one until it fails if you will have to pay for it - it may never fail while you own the car.

MamiLS430

I contacted our Lexus dealearship to find out the skinny on the 70,000 warranty regarding the knock sensors and they told me that it covers ONLY "Internally Lubricated Components".

That would be a NO!! Ha!! Oh well.....I tried.

usermel

If you purchased the cars used it could be an issue that already was there but didnt pop up till you drove it a while longer. The previous owner may not have taken as good care of the car as possible or it could be luck of the draw and you just got a car that's knock sensor went bad.

The bright side is this, all owners of these cars will tell you that if you do all the services required or at least change the oil on the regular that your ride should be problem free outside of normal wear and tear. I just had the front driver and rear driver suspension replaced and it wasn't a normal thing to occur. Sometimes things just happen but trust that this car may have few issues but not as much as other luxury cars.

I owned a couple Benzes and they are great looking but, far less reliable. Expect a reliable car but, not a perfect one. There will be issues with any car especially used but, not as much with Lexus than with other car companies!

L.G.N.M

AlexusAnja

I would say the prevous owner probably filled with regular, rather than premium, causing the knock sensor to work a little harder. The ECU is only going to retard and gain as much as it's programmed to, so if you use premium fuel (which is less likely to knock anyway) then I would presume the sensor is "snoozing" most of the time and the ECU is just running normal.

"What fuel do you use" has been discussed to the point where everyone is blue in the face... but save that $.19/gallon now and you get problems later...

MamiLS430

Just called the shop to see if the car was ready and I find out that it was NOT and that the lights are still shining bright. I am SO mad I could scream. Not having the car for a week while waiting for parts, then Thanksgiving, then the wrong parts sent......now they tell me the lights are still on.

I am so confused, angry, frustrated! I only use premium fuel in the car. My hubby didn't think it made a difference and I overrode him on it. My car.....it gets premium.

Also, I realize that no car is perfect so that isn't the issue. I felt that making the change to a Lexus, as highly recommended by people and husband as it was, well let's just say that I wasn't expecting it to have problems less then three months of ownership.

That said, is there anyone who can shed some light on the problem for me. Thanks.....

NYREP1

knock sensors work all the time not just when they detect pinging..and as far as why it happened electronics fail...it sucks but it does happen..the reason lexus has better dependabilty is b/c they over enginered everything and used the better parts for the things they outsource like knock sensors 02 sensors etc etc etc...you could have a kia with a bad knock sensor just as easily with a lexus or a bently

and to add to what the above posters have said knock occurs when the gas in the cylinder ignites before the piston is at the ideal point in its stroke.

http://en.wikipedia.org/wiki/Engine_knocking

usermel

It may be nothing you could have done about this issue of engine knocking if, the original owner used the wrong fuel before you owned it. That could possibly be why your having this issue. I have never heard of a Lexus having a engine knocking problem ever but, was told that it was/is caused by the wrong fuel.

I think that by chance you got a car that the owner used the wrong fuel in due to the price of gas, prior of course to the recent prices falling! Im sure things will be fine for you and am sorry you spent the holiday without your car,I know that was a drag. The rest of your ownership should be great as long as no other hidden bad treatment was done to your LS430 by the previous owner! All the best,you'll be fine!

MamiLS430

Thank you so much for your post. It really made me feel better. This board is full of wonderful people who really love their cars.....or should I say "Lexus". I want to be a proud owner and hope that I soon will be.

I love my car. It is beautiful and I would tell people that I didn't drive the car, the car drove me. It feels like auto pilot!!

Went by the shop this morning and he is getting some wires to go with the sensor. If that doesn't turn the lights off, then a flatbed trip north to Lexus. Again....thanks for the warm thoughts!

tvdias

A Lexus is a very complex piece of machinery and I would not let anyone but a Lexus certified technician work on it. It's not simply about turning the lights off, it's about understanding the root cause of the issue and how to properly correct the issue.

A "mechanic" is not equipped to deal with the multiple computers and electronics that make up this car.

Vern

MamiLS430

Well Vern.....I will have to agree with you. I was over-ridden by my hubby on that. Take it to our regular shop, who is quite certified, but not on a Lexus, my thought.

I was so hesitant but did what I was told. Last time, mind you.

CarguyinGa

There are plenty of people that mean well with the "advice" they give. It just seems that the ones that know the least always seem to know it the loudest and just love to chime in quickly.

The knock sensors have no relation to the VSC system, fuel grade used also has no influence on the longevity of knock sensors. VSC and Trac Off coming on without any other lights is more than likely going to be related to a wheel speed sensor fault. There are other possibilities though, it needs to be scanned by a facility that has the proper scanner to communicate with the TCS/VSC/ABS controller. That will give a code related to those lights coming on. Most shops are not going to have the proper software to communicate with that system on their scan tool.

I currently do freelance work as a diagnostic tech for local repair shops and dealerships, that is one of the biggest problems I go in to solve...people not knowing what relates to particular systems and just making blind guesses rather than facing the fact that they are not fully equipped to diagnose a particular car. Sometimes it is the lack of proper scan tool for the car, other times it is general lack of common sense. The scan tools are very expensive on software upgrades and there are only a couple that will handle the Lexus VSC, it is most likely not cost effective for them to upgrade to the one needed so I can't fault them there. However, I can say they were negligent in thinking a knock sensor code was causing those lights. If the service engine light was on as well as the VSC /Trac off, that could create a possible link, not likely though.

Get it to someone with the proper tools and information.you're wasting dollars while trying to save a nickel in this case.

usermel

Your husband was wrong on his advice to you. I just saw you went to a shop that isn't Lexus certified. Even if they are I say go to a dealership if possible for major issues. For minor issues like oil changes its cool but, your issue will cost more $ long term if the issue isn't fixed.

I think you and your hubby are possibly being shamed as well. Thats one downside to these so-called cheaper guys you can trust shops. The time period it has taken is to long for the issue you have an the bill adds up. Im very disappointed they didnt fix it quicker for you and your husband vouched for them as we'll.

I DESPISE non-certified mechanics because they prey on the ignorant(ME) for lack of knowing whats wrong with there cars. Yu are less likely to have issues like this at the Lexus,Toyota,Benz,BMW,Honda and Ford service department! You'll be fine Mrs. the Lord has your back! Tell your hubby he should have listened to you on this one. I started taking my ladies advice more and she's been right more than wrong! Woman can be very, very wise!