MR DAVE

I have a 2000 rx300 I bought it new for my wife with 20 miles on it. The only time I had a problem with it was when the CEL light came on at about 80000 miles. The car was losing power. codes 1130 171 and 301 came up. I changed both o2sensors "heated" and changed a/f sensor. worked fine until CEL came on again... This time code p0330 came up. Knock sensor....... I now have no overdrive.

One Lexus owner said the fix was to change both knock sensors as well as a new wiring harness. Another lexus owner had a new tranny installed for $5000 only to have p0330 code return two weeks later with no overdrive..

Anyone with simular problem or have a fix for the overdrive please help me

Thanks dave

Lexmex

Never had a similar issue, but I do remember meetya's post. Bad knock sensor and no overdrive go together (retarded timing/rich condition). In this case it is knock sensor number 2, but easier to replace both at the same time.

Meetya

You're screwed :-(

I had to replace my knock sensors, they are under lower intake manifold. That was the biggest job I ever done on any car. To gain access to them you need to:
- Drain all Coolant from Engine
- Remove Extension Tank
- Remove Plastic Engine Cover
- Plastic Intake Hoses
- Upper Air Box (where the filter is)
- Battery
- Remove Windshield Gator (and all motors ~30 minutes).
- Lift Brake Tank
- Remove Fender reinforcment
- Disconnect all hoses on Throttle Body
- Remove Throttle Body (~1 hour)
- Remove Upper Intake Manifold (took me ~6 hours because of that freaking rear stay bolt)
- Jack the Engine
- Remove Left Engine Bracket
- Lift Lower Intake Manifold
- Remove All Intake Gaskets (I would not recommend to reuse them)
- Remove Water Intake (next to Lower Air Intake Manifold)
- Remove Coolant Bypass Hose (also under Lower Air Intake Manifold, you CANNOT reuse it)
- Use 28mm sockets and 3-4 foot wrench to remove both Knock sensors

BTW, No O/D caused by bad Knock Sensors. I can explain tomorrow but right now I have no energy, have been working for 20 hours this weekend.

Here is your knock sensors:


Here is the tool I used to remove them:


Here is one of them removed:


Here is old sensors in my Dad's hands (he helped me alot):


FYI: Each sensor is about $200.

Meetya

Thanks, Ron, it is absolutely worth replacing both of them the same time just spend another $200, and don't be worried about redoing it / paying another $1000 for labor a dozen thousands miles later. I think knock sensors' lifetime is about 120,000 to 200,000 miles. Just replace them both if one of them goes bad. Also it would be stupid not to replace that rubber water bypass hose under Lower Intake Manifold.

Anybody surprised there is a rubber hose that cannot replaced without disassembling intake system? Just imagine if it blows up!

MR DAVE

thanks for the info. I'm ordering two knock sensors and a repair manual.All local auto parts shops don't stock them So I;ll go online . I"ll let you know how I make out with this experiance.

Meetya

Don't forget to get intake manifold gasket kit, 28mm socket and new coolant bypass hose.

MR DAVE

It took myself and my brother about 5 hrs to do job. spent about $450....plus gas and time. A lexus dealer wanted over a grand. I learned more about my wifes lexus than I wanted too... However there were no parts left over... were both happy. The car hasn't ran so good since i can remember..... and no cel........Thanks so much for everyones help... The mechanic at aamco need more time and $$$ to try to figure out why no overdrive... I took lex went on " club lexus "and I saved mega bucks... unlike other lexus owners that rebuilt their trannies

PS: Meetya Not screwed TY

Meetya

Congratulations on the finished project!
What did you use to unscrew that bolt that hold upper intake manifold on the passenger side rear stay?

MR DAVE

I had no problem taking it out. just used a small ratchet"very short". I had a tougher time getting it back in. Had to use a I believe 14mm wrench first. That bolt was the hardest job in reassembling everything.
I didn't have to jack engine either.

evergreen

I had dealer replaced A/C on my RX300 more than two years ago. About a year later, the CEL turned on. Last week, it lost O/D. What dealer told me is to replace knock sensors due to the error code of P0330 at a cost of $1.1K. I wonder the possibility of knock sensor wires damaged by A/C replacement work. The car has only 58K miles on it.

Any comment is highly appreciated.

Lexmex

Probably independent, those knock sensors are in a very difficult to reach place.