New to the forum! Just got a used 2001 430 with 181,000 back in May. Been a real nice car, a car I’ve been wanting since last year. After about. 5k mikes I get a CEL and I take it to Lexus and it’s my knock sensor. They quoted me....wait for it. $2400 to replace it. I politely declined and I’m now searching on how to replace one myself. Seeing how I have beginner levels mechanic experience, I realize it may Be difficult to do myself but possibly not so much. I’m looking on how to replace one if it’ll be a one day process or should I just find a shop to do out cheaper

 

Just take the intake off, unbolt the throttle body (do not disconnect it from the coolant lines like he manual says) and then unscrew the fuel fitting and remove the intake as one big piece. Sensors are right under it, be careful with your intakes variable runner vacuum line on the bottom of the intake when you are removing it as you may not notice it.

A very easy easy job since you can do it at home and don't need any special tools at all, I did it on my car in between working on some other ones and during my lunch one day. Should take someone new no more than 4-5 hours max

 

Where do you live?

Would send you a P.M., but your settings do not allow you to receive messages from other forum members.

I will say this.... Expen$ive knock sensors.

I have two knock sensors from a very low mileage 2002 LS430 engine.

I transplanted the LS430 engine into my LS400.

The LS400 and LS430 knock sensors are different necessitating reuse of the LS400 sensors, engine wiring harness and throttle body. So have a like new LS430 engine wiring harness, 8 ignition coils and throttle body.




https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/934555-transplanting-ls430-3uz-fe-into-ls400.html

The knock sensor wiring harness is suspect. I also have a like new knock sensor harness which is integrated into the starter harness.

Try sending me a P.M. with your contact info.

Am happy to discuss your project.

 

Responded to your P.M. ...and nothing further.
Trust you have plotted a solution.

 

Watch this video. It's very helpful!!

 

Plan on the injector connectors breaking when you remove them

 

I've done this job at least 3 times (the last time was just last weekend) chasing a knock sensor circuit issue and its not as hard as its made out to be, as long as you have some care, know how and the right tools. First of all, change BOTH knock sensors and the starter motor while you are in there. You will also need the rear water bridge gaskets as that has to come off to get the starter motor out. You will thank me later. Secondly, you can get genuine Denso knock sensors for cheap off eBay, DO NOT UNDER ANY CIRCUMSTANCES USE AFTERMARKET ONES! They do not work with the LS430 knock sensor circuit. Its rare for the wiring loom to fail but it is possible, however that requires taking apart the loom to find the break. I'd check for continuity between the sensor plug and the plug at the ECU, can't remember off hand what the two wires are, but I'd just probe them all until you have a circuit. You can remove the manifold without having to remove the fuel rails, an engine crane is your best friend to get it out as its bloody heavy and awkward to remove by hand. Its possible to have it all done in a day if you have the gear on hand. With the age of our vehicles now, the plugs will disintegrate in your hands, namely both knock sensor plugs, the coolant temp sensor plug, the TPS sensor plug, and you will break the locking tabs off the injector plugs. The wires will potentially pull out of the coil pack plugs, and that turns into a major real quick. I've just dodgie'd up the coolant sensor and knock sensor plugs for now, I smashed up what was left of the plugs, put the terminals on the pins directly and filled the thing up with polyurethane sealer to stop it moving about. To get the starter motor out, the wiring loom back there is your enemy. You need a ratcheting ring spanner to make it easier, because those bolts are a pain in the butt to access and remove.

 

The ones off eBay are fake, NTK and WVE aftermarket will work just fine and you won't be rolling dice on a "denso" and will only need to do the job once. Check the sub harness for continuity when you pull the intake

 

I'm having the same issue with my 2001 with 172K. There are allot of options(and prices) for the knock sensors. I came up with part number 89615-30080 for the OE(expensive) but anyone know the part number for the mini-harness?

 

Integrated into starter harness. Well worth replacing with OEM.

 

Having helped a mate with his knock sensors. It isn't a hard job to do but it does take a few hours to remove and replace the inlet manifold. You can do it on your own but a friend helps manouvering / lifting the manifold out / in.

Some jobs/cars you can cheap out with non genuine parts due to ease of replacement and some cars are tolerant to off brand sensors and it doesn'ttake much effort to rectify eg..MAF (2 minutes 3 screws to swap), TPS - 20 minute job O2s an hour or so, For this job ****Absolutely not mess about with non-genuine knock sensors**** unless you fancy doing the job twice (or more) times to fit genuine sensors..... (we did this job 3 times getting to this conclusion).

Get 2 NEW genuine sensors, from a reputable establishment like a dealer or amayama, partsouq etc. Absolutely do not trust ebay sensors claiming to be genuine..... they might be, but my friends EBAY sensors turned out to be genuine fakes. Got the money back for the fakes but the time to do it again you don't get back (but you do get a lot quicker at pulling the manifold).

Wiring will be heat hardened and cracked - we soldered in new sections of wire with new connectors as needed - that worked fine for us. Do check continuity of wiring from sensor connector back to ecu connector- it's a hassle but way less than discovering a wiring problem after the job.

Do renew the vacuum hose for the variable length intake butterfly vacuum canister - the original is now hard and brittle from years of heat. We used generic rubber tubing from a parts store.

Take time to tape over ports to minimise crud inadvertently falling into the head ports (or stuff clean rags in).

Have a vacuum handy to clean up the crud, dust, grime around manifold edges and that has accumulated in the inner V. Its much nicer working on clean.

Manifold gaskets are tough, thick, durable things ...there is a very high chance that you will be able to reuse the originals. We used a very light coat of silicone gasket on them as a precaution to ensure a perfect seal

Manifold clean whilst it's off or not?? Personal preference - I did mine. My mate didn't bother with his. Both drive great.

starter - optional - personal parts philosophy preference - why fix what isn't broken? But then again, peace of mind yaddah yadah... We chose not to change it - the original continues working as intended several months later. Once you lift the manifold the first time, it isn't scary if you need to do it again in the future.