glassmaker

Quick question. I am getting ready to change the knock sensors and sensor wiring harness on my ’99 ES300 with 200K on it, and don’t want to have to pull everything apart more than once if I can avoid it. The plan at the moment is to replace any other potential problem parts while I've got things torn down to get to the knock sensors and harness. The parts listed below are what I figure I should take care of, based on other threads I’ve read. Have I missed anything? Are there any suggestions about other parts I should replace while doing the job or things I should beware of?

knock sensors
knock sensor wiring harness
intake manifold gaskets
bypass hose
throttle body gasket
rear spark plugs
bank 2 air/fuel sensor (maybe)

Thanks.

PFB

You may want to consider doing the rear valve cover gasket if never done.


Also make sure you’re getting original Lexus knock sensors, if not there is an excellent chance you’ll be doing the job twice.

LeX2K

You've got it mostly covered, but for the love of god use only OEM parts. If I had a penny for every time I've read about someone doing this job then, "my CEL is on after changing knock sensors".....
100%.

glassmaker

Thanks. I’ve been agonizing over dropping another $400 for the OEM sensors since I’ve already spent a pile of cash recently on other parts, including 4 “almost OEM” struts (I went with the KYBs for a Camry, and am happy with them); timing belt, water pump, seals, and associated hardware - all OEM; and passenger side CV axle, sway bar links, etc.

I know I’ll probably regret the decision down the road, but because I’m pretty much out of cash now I’m going to try and get out of this one cheap with aftermarket knock sensors. If rolling those dice comes up snake-eyes and I have to do the job again later with OEM sensors, so be it. At least next time around I’ll have some experience pulling them out. If that happens, I’ll post again here so you guys can rightly tell me, “We told you so”.

As far as the valve cover gasket, I wouldn’t have thought of that. Is that a common issue? (I assume common enough to mention it.)

Thanks again.

PFB

The leaking valve cover gasket is a VERY common issue, especially the rear one. The bolts should be replaced by Lexus dealer supplied new ones. The old ones are usually stretched and may cause leaks

I feel for you for not being able to afford OEM knock sensors now, but really after market knock sensors seldom work. See what you can do. You can probably buy them online from a Lexus dealer much cheaper.

good luck

glassmaker

Thanks. Sounds like a good plan to do the valve cover gasket too, while I've go things apart. And that $400 price I mentioned for the knock sensors WAS an online "discount" price on two OEM knock sensors. Regular dealer price was even higher - $245 each. I did look around some more online since and found another dealer discounting them to $165 apiece, but that still puts a pair of them out of my range right now, especially since I'll likely need at least one air/fuel sensor too, according to my code scanner. And I know those are "special" too, so will be installing the correct OEM unit in the hard to reach spot (B1S1?) when i do the knock sensors and harness. (Another $130, or more.)

The car I picked up cheap from a friend a couple of years ago is turning out to be anything but. However, it will probably have enough new parts on it by the time I'm done to easily go another 200K. (I hope.)

glassmaker

I just wanted to say good call on the valve cover gasket. On close inspection it already appears to be seeping just a little bit of oil. Not much right now, but it obviously isn’t going to get any better in the future if left untouched.

jetspeed

Hey. New poster here and have been browsing about this problem for a bit. I'm wondering which dealers typically will have the best prices on parts? I'm in Canada so I'd have to get it shipped here but parts are generally cheaper in the US than Canada.

I did find this and I see 2 different parts numbers that fit my 2000 ES 300. Does anyone know what the difference between the 2 are? I know there are 2 sensors. Do I need to order one of each or something?
https://www.lexuspartsnow.com/oem-le...tra2=&filter=()

glassmaker

If you take a closer look at the parts description you'll see that the difference is the production date of the cars they fit. One is meant for ES300s built from 08/96 - 08/99 and the other for 08/99 and newer. This page will tell you where to find the production date in case you don't already know - https://www.lexuspartsnow.com/servic...tion_date.html

jetspeed

Thank you!