shiren79

Hello all,

A new member with 99 ES300 (friend of mine's car) has issue with check engine light.
Codes came up (P0325,0330,P0446) few weeks ago, car showed several following symptoms;
a) 4th gear would not engage
b) No kick-down at any speed.
c) Engine stalled once at street light, upon acceleration. Was not able to restart the engine.
d) Excessive fuel consumption.

I was told that 4th gear issue is Lexus thing, a limp mode activates when CEL is on. Bit ridiculous I must say, but what can I do, right? Of course non-functioning knock sensors cause decreased fuel efficiency, so I'd relate a&c to knock sensors..

And as for the stalling engine, I would probably have to assume that it's related to knock sensors. But I'm little bit skeptical because as far as I understand, knock sensors only detects detonation and help ECM to adjust the amount of fuel injection, and when they fail to perform their job, engine injects more fuel to prevent lean condition. So, engine running rich wouldn't stall, but my understanding of how knock sensors work may not be correct. Or perhaps motor oil leaked through camshaft position sensor O-ring and caused it. I'd have to check it.


So, here's what happened when I checked up on her car. I erased the codes and went for a test drive, and as soon as I hit the highway, transmission did not go into 4th gear, CEL illuminated. I went back, scanned the codes, and both P0325 and P0330 came up. No VSV code at that moment as it was one driving cycle. I've worked on dozens of cars, codes never came up that quick unless they weren't getting signal from components at all. Plus, bot knock sensors didn't sent data at all? Uh oh. Are you thinking what I'm thinking? Yes, the harness...

I would have to check the resistance of harness, but do you think it's the harness instead of knock sensors? It'd be a great news since this dreaded sensors cost $150 (Denso, 1qty), and $450 at Oreilly's. I know you guys have more direct/indirect experience on this specific model, I would like to hear your opinions.


P0446, defined as 'Evaporative Emission System Vent Control Circuit'. I understand that engine has several VSVs for various emission control system, so which one would trigger P0446? I'm guessing it's VSV for vapor pressure sensor or VSV for Evap, but I'm not 100% certain. I really wish I had Toyota Mongoose to activate the solenoid manually..



It really is a long thread, I appreciate your patience. I'm going to let her know what to buy as soon as I hear from you guys.
Thank you again!

PFB

Not sure what the specific problem is, but if you do get new knock sensors, make sure that you get the ORIGiNAL Lexus sensors, and NOT aftermarket ones.

Although much cheaper, the aftermarket ones are giving problems to most peoole that tried to use them, and since job is relatively labor intensive, it's not worth it.


Phil

shiren79

Thanks for reply Phil. I'm also aware of reliability issue with aftermarket parts, so I'm not going to get parts with no reputation at all. I'd have to talk to a friend works at worldpac, see if he can give me a good deal.

Some weird thing just happened today. She told me that 4th gear engaged again, worked perfectly all day. CEL was still illuminated though. Day was pretty warm, 75 degrees. It was really cold for weeks, that's when the symptoms developed. What a coincidence.
So, a knock sensor is just an acoustic device with piezocrystal, conductor, and some sort of resistor (forgot the name), would it really be dramatically affected by weather? I know fundamental of how parts work, but I have very little knowledge of characteristics of each material.

My thoughts are all bunched up together, I know it's not leading me to anywhere at all. Jeez. I would normally tell them to replace parts to be safe, but she's going through a hard time since she lost scholarship. That's why I'm seeking for alternative(or definite) solutions other than replacing expensive sensors.

tomf

Sounds like a bad knock sensor. For a replacement I used STANDARD MOTOR PRODUCTS Part # KS81T. Cost is about $100 from rockauto. It worked perfectly.

If you are paying someone to do the replacement the cost will be fairly high because the plenum needs to be removed to access the knock sensors. This link http://www.findonefindall.com/toyota...ock_sensor.htm will give you an idea on what needs to be done to replace it. Also, it is a good guide if you decide to replace the knock sensor yourself. Also replace the bypass hose while you have access to it and the bank one (rear) spark plugs (if they are anywhere near being due for replacement).

craigndee

Thanks for all the input guys. My issue has been resolved. I purchased two knock sensors from the TOYOTA dealer and a new harness. Codes have not returned. The part numbers for the Lexus and the Toyota are the same but the price was almost $150 cheaper for the ones from the Toyota dealer. I did have to provide the Toyota guys with a part number. Look up the part on an online Lexus part store and get the part number. The REAL sensors solved my problem after the third time I tore this thing apart. Moral of the story always buy sensors from the dealer to get the real ones. Avoid my nightmare. Good news is Autopart international let me return the aftermarket non working sensors and harness.

lostape45

Glad to hear you fixed your problem. Funny how OEM parts make so much of a difference.