Replace Knock Sensors?

[joeypruett]

okay - question number 2.

like the previous post mentioned, my wife's LS400 (1992) supposedly has knock sensors #1 and #2 that are bad and need replaced. the dealer quoted $750 total for both. there are no engine or other lights on and i'm not sure if i should proceed.

any thoughts?

thanks again,

-joey

[SKperformance]

Moved to the LS forum

[lexus082]

I just looked up a knock sensor online and it runs $137 for a OEM Lexus Knock sensor. (not sure if its the same on your car mines a SC400 same engine), but the part number for my car is 59615-50010. Pretty sure its the same part but it could be a different number. So $274 (using genuine parts) if you do the job yourself. I do not know the difficulty of the job, might be easy, may not be. I would do a search on this topic and see what you find. You could also search the SC forums for the same thing since its the same engine. That would save you approx $500 if you could do it yourself.

[joeypruett]

I just looked up a knock sensor online and it runs $137 for a OEM Lexus Knock sensor. (not sure if its the same on your car mines a SC400 same engine), but the part number for my car is 59615-50010. Pretty sure its the same part but it could be a different number. So $274 (using genuine parts) if you do the job yourself. I do not know the difficulty of the job, might be easy, may not be. I would do a search on this topic and see what you find. You could also search the SC forums for the same thing since its the same engine. That would save you approx $500 if you could do it yourself.

thanks. dealer says it's difficult to repair as it's deep inside the engine.

sounds like you would definitely replace them? the car doesn't knock that we can tell - but there may be other benefits. what's really odd is that we don't see any dash lights indicating failure.

-joey

[mehullica]

You can change the knock sensors and wire harness without removing the intake manifold. Remove the EGR valve, PCV hose and you can get you hand into the V area of the block. A 27mm socket and small rachet with a flex head and the job is done.

[lexus082]

Did your check engine light ever appear? How did the dealer come to the conclusion your knock sensors were bad.

Just guessing, but I would hope that the beginning of your response would sound like this: check engine light came on, had it diagnosed by dealer, pulled code "--" which indicated the "knock sensor" was failing. Also, is your check engine light still on?

[joeypruett]

Did your check engine light ever appear? How did the dealer come to the conclusion your knock sensors were bad.

Just guessing, but I would hope that the beginning of your response would sound like this: check engine light came on, had it diagnosed by dealer, pulled code "--" which indicated the "knock sensor" was failing. Also, is your check engine light still on?

engine light came on intermittently, had it diagnosed by the dealer, pulled code, didn't ask about the code, i'm assuming it indicated knock sensor 1 and 2.

engine light has been OFF since the visit several days ago.

if it still needs replaced, my grease monkey mechanic could probably do it for 350 - according the sage and welcome advice on price and ease of repair.

-joey

[nc211]

Joey, what kind of gas do you use?

[joeypruett]

Joey, what kind of gas do you use?

91 octane, usually from costco.

-joey

[nc211]

Joey, what kind of gas do you use?

91 octane, usually from costco.

-joey

Have you tried a can of Seafoam in the gas tank and blown out the engine on a back road yet? Seafoam seems to work really well on these cars to clean out the fuel system. I've had good luck with it in my car. Might be worth the $5bucks to see if it cleans out some injector buildup? How old are your spark plugs?

I would hate for you to pay all that money only to realize that you could of done the same thing with $50 bucks in new plugs and a can of Seafoam. Not saying that it would fix it, but maybe the knock sensor is working fine, and that it's just telling you that your engine needs new plugs and better flowing fuel through a couple of injectors?

[joeypruett]

we'll try it, thanks.

[kingofoverkill]

You can change the knock sensors and wire harness without removing the intake manifold. Remove the EGR valve, PCV hose and you can get you hand into the V area of the block. A 27mm socket and small rachet with a flex head and the job is done.

With this procedure work on a 1996 LS400?

[Piazo]

My 1998 LS 400 has the check engine light on, for years  now,  and keeps throwing codes  for the Mass Air Flow Sensor and the Knock sensors . I think the dealer called them the Limp- Mode sensors / anti knock sensors .  Years ago I had Chipped the car with a performance chip , but disconnected it when I started having these problems . Anyway,  every time we clean or replace the sensors, the check engine light comes on again a few days later . I thought it could be the on-board computer. Dealer said the older computers don't have a self-diagnose feature like the newer Lexus's do . And ideas ?