natdhaeka

Hi, I am new to this forum and I live in Adelaide, South Australia. I recently bought a Lexus LS400 July 1993 model with 179000 kms. The check engine warning light comes on within 5 minutes into driving with simultaneous reduction of power/acceleration. I took the car to my local mechanic with a copy of the how to read and clear diagnostic trouble codes from LexLS.com. On checking, the code was 52 - the number 1 Knock Sensor signal. My mechanic hasn't worked on Lexus car before and he dosen't know what the underlying problem is. Can someone give me some guidance about what the underlying problem could be? Thank you very much for your help.

Nat

LiCelsior

iTrader: (32)

search and see what other people have come across. search like "code 52*" or something.

natdhaeka

I have looked at the previous threads regarding engine code 52. However, I am unclear about what the underlying problem really was and what repairs undertaken by the member corrected the underlying problem and disappearance of the code 52. Can someone please help me urgently? Thank you

Photoinc

I had a knock sensor issue with my 88 turbo Supra. Chased that problem for a while, changing knock senors didn't help.
Turns out it was the wire at the knock sensor connector. When the shop installed the 2mm metal headgasket, as they were pulling the head off, they forgot to pull the knock sensor wires, and put undue strain on it but did not totally break it. On a whim of desperation, I pulled the connector off, twisted the wire about 10 times and plugged it back in, cleared the codes and believe it or not, never had a knock sensor code again. In fact a couple of other friends had the same issue, I told them my fix, and it worked on their cars too.
On the supra 7MGTE engine the sensors (2) were mounted on the block between the freeze plugs. I imagine, never looked, the sensors on the LS are in a similar location. I don't know how many it has either, maybe one on each side or two.
Knock sensors don't usually fail, the failure comes from lack of signal.

I eventually got a used connector that was pretty snug and spliced it on to the sensor wire, right at the sensor.

Do the twisting test, be sure to clear the codes before you start the car.


keep us posted

python

iTrader: (4)

i had to replace my knock sensors, i am going to give u detailed information and this isnt going to to be nice so i hope u r sitting down...
the knock sensors are under the intake, it takes about 5-6 hours labor to do this, there are 2 knock sensors that u need to replace, DO NOT REPLACE JUST ONE! there is one on each bank of the engine, now listen to what i am about to tell u PLEASE!!!!!!!
REPLACE THE CONNECTORS THAT U GET FROM THE DEALER, THEY WILL KNOW EXACTLY WHAT U R TALKING ABOUT WHEN U ASK THEM FOR THESE AS THEY ARE A COMMON PROBLEM!!!!!!!
the knock sensors are expensive, if u use aftermarket parts u r asking for trouble... the sensors from the dealer are around 120.00 or more for each one and the connectors are cheap, maybe 15 dollars or so for each one, if u can afford it, have the intake cleaned thoroughly!!
i am sorry this has happened to u and even more sorry it happened to me, anyways good luck....
also this problem will effect the way the car accelerates and shifts, i thought my damn tranny was going out

Photoinc

Key point here is replacing the connectors, they are the weak link and probably the main problem, however, if you have to remove the intake just to change the connectors, might as well replace the sensors too and be 100% positive.

If the starter has never been replaced I would recommend doing that too while your in there.

python

iTrader: (4)

good point

Photoinc

Here is a link to a photo that shows one of the sensors in the lower right third of the photo. It's has the gray connector with the gray wire cover.

http://img149.imageshack.us/my.php?i...e447Medium.jpg

natdhaeka

Thank you very much for your responses. I will take the car to my local mechanic this week and see whether he can fix the problem - nat.