Question about 1998 Lexus ES 300

1 Answer

Have a 1999 lexus es300. Getting indications that knock sensors need to be replaced. Car has 144k miles. What do the knock sensors do and how easy / tough to replace?

Posted by on

  • jaygant1 Oct 03, 2008

    also my overdrive doesn't work either

×

1 Answer

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    Hot-Shot:

    An expert who has answered 20 questions.

    Corporal:

    An expert that hasĀ over 10 points.

    Mayor:

    An expert whose answer gotĀ voted for 2 times.

  • Expert
  • 36 Answers

If you have some common tools the knock sensors are no big deal.  If you take a lexus they will make is sound like you need to completely disassemble the engine and scare you off.
First, do you really have a problem with preignition causing real knocking due to carbon buildup, or diluted gasoline or do you have failed knock sensor(s).  Try to decarbon the engine first.
There is a technique used with water being sprayed into a warm engine intake.  This will clean up the valves and carbon buildup which can result in engine knocking.  

The job will be a couple hundred for the parts and a couple hours of your time.  After you are done, you have entitled yourself to approximately $500 in new tools for your tool chest since this is what Toyota and Lexus will charge to fix (about $1k+).

You will need to buy the following to address the knock sensors and a couple other items while you're in the neighborhood.
- 1x upper intake plenum gaskets - 2x lower intake plenum gasket - coolant bypass hose found in the same area as knock sensors - 2x knock sensors (bank1 and bank2) - short pig tail cable which connects both knock sensors to common wire harness. - toyota antifreeze  (2 gallons, if i remember correctly... when mixed to 50/50 (antifreeze/ water) you will have 4 gallons.
drain the radiator drain the front of the engine using the engine drain plug - this plug is on the front right side facing the engine, behind the right hand exhaust manifold. (this will lower antifreeze enough to avoid dumping antifreeze all over the engine later) remove the air filter box remove the connections into the throttle body remove the cable from the throttle control remove the upper air intake plenum remove the two lower air intake plenums remove the antifreeze fill port
Knock sensors will be in the valley between the lower intake plenums.  You will need to remove the rubber antifreeze bypass hose (little short hose blocking access to the knock sensors).
By the way, the reason you bought a replacement, is that if this short hose splits from normal wear, you need to spend this money and effort to reach it, so just do it now.
The little pig tail cable which connects both knock sensors to the wire harness is said to cause a big majority of the problem due to the plastic getting hot and brittle, falling off and shorting to the engine.  While in this mode the engine thinks knock is occuring and starts to retune the air fuel mixture to get rid of the knock until it goes into minimal operations mode.
After replacing the knock sensors (and tighten to torque specs), replacing pig tail cable, and reinstalling your new short by pass hose.  Replace the lower gaskets, antifreeze fill port, lower intakes, upper gasket, upper intake, air intake, air filter, reattach everything, reconnect all the rubber lines you pulled off, make sure there are no splits in the air intake passage anywhere, retighten the engine antifreeze drain plug, and the drain on the bottom of your radiator, and your done!
Don't forget the easy stuff.  Dilute the antifreeze with water and fill the radiator and overflow tub.  Run the engine for several minutes until its hot and opens the thermistat to allow antifreeze into the empty engine cavities.  Turn the engine off and get a cold one as the engine cools.  Once absolutely sure engine is cold, refill the radiator with antifreeze and refill the reserve tub.  Do this at until all the beer is gone and you are both full of antifreeze (in one form or another)..... obviously red stuff in the car, amber down the gut.

Posted on Mar 16, 2009

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Can you show me the picture of a knock sensor for harrier 1mz engine en how I can repair it


images for a knock sensor for harrier 1mz engine

2000 Lexus Es300 Knock Sensor - Location & Repair ...

? 2:20
https://www.youtube.com/watch?v=bDSmfxb1o1E
Jun 25, 2012 - Uploaded by RashaadRahh
2000 Lexus Es300 Knock Sensor Replacement - Location & Repair. ... Check engine light comes on and you ...

Jan 07, 2016 | Cars & Trucks

1 Answer

Would the knock sensor on a 99 Lexus 300 cause the transmission to not shift out properly?


Yes. Thanks to Dennis Weid, Robert Garcia, Colin Strickland, and "gingo12670" on this website, that is what I found to be the problem causing my 2000 ES300 to not shift more than once into overdrive without shutting my car off. Apparently if your knock-sensor(s) is bad it will send a signal (or lack of an expected signal) that will cause one of the "brains" to not allow a shift into overdrive since that would only aggravate a knock situation. The sensors are not an easy fix as the intake manifold must be removed. It cost me $750, but I am happy as a clam since the solution has eluded me for too long. My Lexus has over 200K miles but after flushing my transmission to no avail, but just now replacing both knock sensors, it now feels once again like a new car.

Jul 21, 2014 | 1999 Lexus RX 300

1 Answer

Where is the knock sensor located in 1999 lexus es300


the knock sensors are located underneith the intake manifold on either side of the engine block. you have 2 of them

Aug 31, 2012 | 1999 Lexus ES 300

1 Answer

How to replace knock sensor on 1994 Lexus ES300


Hi,

This is a big job, you will need to remove the intake manifold and various other intake components to get to the knock sensor, which is sitting in the V gulley of the engine.

But basically you need to remove all inlet tract components, and the top cooling system components, then remove inlet manifold and there you will see the knock sensor.

Good Luck

Thanks

Jason

Aug 18, 2010 | Lexus ES 300 Cars & Trucks

1 Answer

LEXUS es300 oil light stays on oil level full


Check oil level sensor, replace if necessary. also, does your engine knock or make a tapping sound?

Mar 28, 2010 | 1994 Lexus Es 300

2 Answers

92 lexus es300 knock sensor


Need to remove the upper and lower air intake manifold.  There are two knock sensors for the front and rear pistons banks.  If you plan to do this yourself it is about 1 to 2 hours.  While you are at it, there is a short coolant bypass hose sitting in the same spot, replace it.  Another problem with the knock sensor is the wire harness used to connect the two knock sensors into one connection sometimes wears out and contacts the metal on the engine causing false signals to the ECM, so replace this cable also.
Just did this last summer on my 99 ES300.  Pretty easy.
DIYr

Mar 01, 2009 | 1999 Lexus ES 300

3 Answers

Where is the Knock Sensor located on a 1994 Lexus ES300


  1. located on top of engine below intake manifoldgraphic.aspx?mod=reptiff&module_id=1&session_id=%7ba7aa889f-b7e3-42e1-9ece-3476a2533f69%7d&image_guid=95d24086&print_bw=0&

Jan 06, 2009 | 1994 Lexus Es 300

2 Answers

Transmission on my 1999 ES 300.


Flush the fluid every 30-45k miles. I work for lexus and they make solid cars and transmissions but some es300 transmissions from that year range fail (a very small percent) they do only replace transmissions. After the replacement the cars are fine, its not necessarily anything the owner did.Ive seen mixed results from shops that rebuild these transmissions as they don't do them everyday, those shops see alot more gm ford and chrysler vehicles and many of their models fail before 100k.

Nov 20, 2008 | 1999 Lexus ES 300

2 Answers

1999 lexus es300


This has been happening to my car as well. It typically happens when your oxygen sensors start to wear out. Mine does it once in a while and I have the local auto store reset it. Go to your nearest auto store and have them tell you what code it is and ask them to reset the OBD so the light goes out. If the light comes on right away and the code has to do with your oxygen sensors, have them replaced. There are three, two are easy to replace, one takes some effort as it is in a tough to get to spot. The dealer will charge you a fortune to replace them so do it yourself or through a local mechanic. It is a very simple task other then the access.

Jul 15, 2008 | 1999 Lexus ES 300

Not finding what you are looking for?
1998 Lexus ES 300 Logo

2,070 people viewed this question

Ask a Question

Usually answered in minutes!

Top Lexus Experts

yadayada
yadayada

Level 3 Expert

60769 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

21949 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

6811 Answers

Are you a Lexus Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...