Preventative Maintenance
 

How common is the knock sensor issue on these cars? I recall Toyotas having codes thrown from knock sensors and harness problems often. I am pulling the intake and doing valve covers in a week from now. Car isn't having any issues, but I'm debating pulling the lower intake and replacing the knock sensors and harness while I'm at it just to prevent a future problem. I just did the water pump, thermostat, and radiator and would hate to open up the cooling system again, however, this would be the time to do it.

Thoughts?

I am replacing plugs, and the rear three coil packs, as well as the pcv valve. A new IAC valve and all new gaskets of course. Is the extra trouble and cost of parts worth it just because it "might someday" throw a code? Has 134,000 miles.

For those of you who have been following my rebuild of this rx, I am fixing it up for my mother and will be taking it to her 1,500 miles away. I am trying to give her a problem free car for many years. Her current car is on it's last legs and I am sending money for repairs a couple times a year. I don't want to have to pay a mechanic for the same work I do anymore lol.

Just my observation here, the knock sensor isn't a common issue on these cars but if your car has a history of getting related CEL codes or showing shifting problems into 4th..then definitely do it. Since you're removing the plenum to do the rear valve cover its not much more work to remove the lower.., you can make your assessment with the wiring condition. On other forums i've seen instances of rodents making nests and evidence of chewing the knock sensor wires that caused the issues. Good luck!

FWIW, by your other recent posts and interest of refreshing and preventative maintenance you may opt to replace the injectors and seals with new or OEM remanufactured injectors if you choose to remove the lower plenum.. Though flow testing/cleaning services are available, it is a pricey service per injector. Sets of 6 remanufactured can be found under $60.

The knock sensor code often kicks in after about 150k miles and 10+ yrs of service.

Since you have it apart, I would suggest do the replacement. Check our DIY section. Use OEM sensors which go with your vin.

You will be paying for few extra gaskets but will be save boat load of labor time.

Salim

I know I should.. its just, there is $1,000 in things I could replace because they might have a problem down the line. I am at my budgets end and I am putting some of my money with it now too. Don't mind putting some with it. But its like, the starter could go out, or the alternator. I can't replace everything on the car. But at least those things aren't as labor intensive as the knock sensors. How important is it that OEM sensors are used? Sounds expensive. You don't think some from NAPA would work? Their quality seems best out of the parts stores.

Has the starter ever been replaced or rebuilt? At 134K it is due to cause problems. That said, it is an easy and inexpensive repair; new contacts and plunger are $20 or so.

Alternator and starter are accessible any time [unlike v8 starter in Lexus line]. My suggestion was based on your milage and you are almost 3/4 of the way there. Please do actual pricing instead of guessing. You will need couple of more gaskets and coolant.
I feel so strongly about OEM sensors that I would say dont do the sensor change if you plan to use after market.
Salim

Can you give me your honest opinion on this though? I don't see why a could't trust Denso, and the price is incredible.
https://www.ebay.com/itm/2-DENSO-Kno....c100005.m1851

i wouldn't have a problem with a NAPA knock sensor. Its a non moving part and nothing special about it. It's just a piezoelectric circuit. They typically last the ownership of the car. ..but considering the price of the NAPA knock sensor vs OEM Toyota sensors on Amazon..i would go with the OEM 2 sensors 34 shipped.

No opinion.

There are knock offs and factory rejects which can make their way to the grey market. You really need to purchase from a reputable seller.

Since I DIY, I save on the labor and am willing to pay more for the parts. I can't afford debugging or doing the job twice. I paid full retail price to my local Lexus parts. [Note model number is not enough, you need to take the vin to get the right knock sensor].

Salim

Just as a close to this thread, I did the lower intake and knock sensors and harness. Job went well and after a week of driving, no issues with the Denso sensors and harness I used. I am more familiar with the harness being an issue just due to heat and age in the valley. Nothing looked bad, but at least now I've done all the big jobs on this vehicle. I caught and re-used my coolant to make it cheaper. Just drained form the petcock valve worked good, nothing came out from the intake when I pulled it, so no mess.