TxTarheel

I have read many posts concerning this code but I wanted to get a specific answer based on my experience and also relative to fuel additives. Briefly:

80,000 miles, 2001 RX 300. CEL popped on while driving interstate returning from a trip last Sunday, not long after getting a fill up. Once I got home I opened gas cap and did not hear a pressure release so I thought that might be the issue, so reseated cap and cleared codes. No problems with in town driving for several days, then five days later (Friday) while driving on interstate again, CEL popped back on. Opened gas cap again and did not hear a pressure release so decided to get a replacement cap. Replaced gas cap with aftermarket one I picked up at AutoZone and after some reading decided to also use MAF cleaner to clean sensor (outside bulb was a little dirty, inside wires were still shiny). Reset code and drove car a few city miles to test, no more than 50 mph, and it seemed fine. Idle was fine, no stumble, engine smooth. Was driving again a few hours later under same conditions and within 10 minutes CEL came on. Went to AutoZone and had code read – P0330. So far OD has been available the two times we were on the interstate and CEL popped on but we have not had it on highway today, since having the code read at AutoZone.

FYI: Car has been consuming oil for last year. Oil light would pop on after about 3000 miles and I would have to add a quart to get to my normal 5000 mile oil change. Thought I might have oil gel issue so took it to dealer this week (Tuesday) for that issue. No CEL then and I did not mention it since it was a few days after we returned from our trip and reset the gas cap and the CEL. So dealer removes valve cover and says no oil gel and that engine looks good. They can find no leaks of any reason for oil use and suggested a faulty valve seal, but not sure. They suggested I wait and try to monitor it to see if it gets worse. No smoke from tail pipe, or other signs of oil in combustion chamber but they said it might be such a small amount that it is not showing up.

So is there any way this oil in the combustion chamber (if it is in fact in there) is causing vibration or fouling and that is setting off the code? From what I read this code is not related to an actual knock or ping in the engine but the code indicates a failure in the knock sensor itself. Is that correct? I also read where someone added several cans of fuel treatment over the course of several fill ups and it cleared his P0330 code. Could the knock sensors be fouled, maybe even by oil in the combustion chamber? Would it hurt to try the additive before going the repair route? We bought the car new and have always used 87 octane, either name brands or Costco. Also in August 2010 CEL showed codes P1130 and P1150. Bank 1 and bank 2 A/F sensors were replaced. Then in October 2010, code P0440 popped up and replaced charcoal canister, fuel cap and VSV. All work done at dealer.

I did not have the code checked until today so I cannot swear that the P0330 was on before or was the only code on before. But it is the only code that shows up now. I am now thinking that maybe the P0330 was setting off the CEL all along and maybe the gas cap and MAF were not an issue at all.

Thanks

TxTarheel

UPDATE: Took car to the interstate entrance ramp, about 3 miles away, and it drove normal. Idled at about 750 RPM with the air conditioner on. Once on the interstate it behaved normally and ran about 2600 RPM at 70 mph for 10 miles. Exited interstate, did a U-turn under bridge and re-entered interstate and car would not engage OD, remained in 3rd gear. "OD OFF" did not illuminate on the dash. Car ran at 4000 RPM at 70 mph. Exited interstate about 3 miles later and pulled into parking lot. Shut off engine and let car sit for 5 minutes. Then re-rentered interstate and car acted normal the rest of the way home. Went into OD as normal and performed normally upon exit, about 7 miles later.

Should I conclude that once the car is in OD it will stay there until it downshifts out and then it will not go back into OD until you turn it off for some (???) period of time? I expected it would either not go into OD at all or would cut out of OD once the engine reached a certain temp? My temp is normal, just below half way. It was already about there when I initially entered the interstate and pretty much there when I re-entered the interstate after the five minute shut down period, so engine temp does not seem to have an effect on engaging OD. I am pretty confused at this point.

salimshah

I will urge you (and others) not to attack the problem randomly .. well meaning efforts really complicate the situation. Invest in a code reader or go get the codes read.Record them and reset them once and wait for them to come back and if they do then take corrective action.

Lot of things in your post here. I will restrict my answer to your thread title ... knock sensor.

Once the CEL comes on (due to Knock sensors) the O/D is not locked out immediately. Only after the light has been on a while the O/D is locked out. You can reset the light (by the reader or disconnecting the battery) and then the process repeats.

My experience showed me that I could clear and go for a month or two without CEL coming back and as the time went bye, the CEL would start coming back more frequently. If I used premium gas the CEL would come less frequently. Hot day driving would trigger CEL too.

If you dont hear the engine knocking then most likely the knock sensor(s) has gone bad. The problem can also be in the wire harness. Please read up the DIY an decide to pay the piper or DIY.

Salim

TxTarheel

But in my case it was not locked out, if you mean lock out until you reset the CEL. I turned off the car and after I restarted it the OD worked again, even though the CEL was still on. Or did I misunderstand you?

salimshah

If you drive enough with the CEL (due to knock sensor code), OD will be locked out. It does not lock out on the onset of CEL. The lockout is not permanent and gets reset on turning the vehicle off (just like you stated). Lock out is a side affect of the CEL In any case the diagnosis should be based on error code. If you are getting the code, you can have the output observed on oscilloscope by a trained mechanic, who should be able to tell you if the sensor output is bad by looking at the wave shape. I decided to just replace them.

Salim

hypervish

It sounds like the sensor is bad, and needs to be replaced.

But, it can be a tank of bad gas. Have you gone through a full tank of gas? Try a tank of 93 with a fuel system cleaner.

I believe this is the code for the second bank knock sensor, which is located under the intake manifold.

carguy07

What I'm reading in the manual makes me think that this code is only for a bad sensor or harness, not for excessive knocking or pinging. Does that sound right to you?

lserlohn

I remember that my car ran at 3000 RPM at 70mph, with air conditioner on.

[QUOTE=TxTarheel;6720220] Car ran at 4000 RPM at 70 mph.

TxTarheel

[QUOTE=lserlohn;6721384]I remember that my car ran at 3000 RPM at 70mph, with air conditioner on.

Yeah, mine runs about 2600-2700 in OD at 70 but it would not upshift and ran about 4000 RPM's this one time. Took it out today for drive on the interstate, about 20 miles to my destination and 20 miles back. No issues, it went into OD just fine. On the trip out I had to stop once due to a lane blockage but it went right back into OD when I resumed the trip.

Carguy, I think you are correct. The code indicates a bad sensor, not pinging or knocking. If not for the overdrive issue I guess you could ignore it for quite some time. I still don't understand why a CEL would disable traction control and skid control as a routine matter. That seems dangerous to me. Maybe there is some connection that I am not aware of.

vietalogy

I'm also having this problem and I the process in getting knock sensor and replacing them asap, hopefully this fixes the OD problem.

salimshah

[QUOTE=TxTarheel;6721866]I think the traction and skid control are not disabled. When you turn the ignition off the additional warning lights go off and get triggered after a bit of driving. It seems to me they convey some hidden code (which is not known to me).

I agree that most of the problems are due to sensors going bad instead of senors reporting correctly that some thing is wrong in the system they are monitoring.

Salim

vietalogy

Since I got a friend that has a shop I called Lexus and used his account and got both sensors, wire harness, 3 gaskets for $384. Only bad part is that they have to order it and I have to wait until Tuesday to get the parts and fixed.

Androman

I know this is a super old post but, my 2001 RX has this code. And you said "If you dont hear engine knocking then most likely sensor gone bad". Well, I do hear engine knocking I can even tell right when it knocks, and i lose OD, Ive ran a couple bottles of seafoam in the tank, and a few others, but hasnt changed. Also, right before i got this code, i got one for the front A/F sensor, i unplugged battery and reset comp, the A/F went away for a month or so, then all the sudden, i had to gun it while turning in a intersection and right in the middle of it taking off, it kinda studder a bit and BAM CEL then TRACK. Then this time it was the knock sensor. But like i said, ive run multi- fuel cleaners, reset comp multi times and still knock code.

salimshah

The question is .. is the engine suffering engine knock that the knock sensors + ECU can not compensate [altering ignition timing] or the sensors+ wire giving faulty information. You can have an expert/tech make the determination or start replacing parts. If you are paying some one else, let them make the determination and only state the problem [do not diagnose them]

Additional data for you is that the life expectancy of the knock sensors + wire is about 150-170K miles. [limited observation based on personal experience and reported problems on CL]

Just be aware that the cost of knock sensor replacement is high and there is a chance that your issue can be knocking due to high carbon buildup or bad timing [bad timing is a remote possibility].


Salim

Androman

Thank you for the reply.

Well, before I had any codes, I was consuming SOME oil, maybe a qtr of a court every month. So I set forth on a mission to seafoam everything. I ran it in the oil many times, changed oil many times, also ran it in the intake after the maf, I even took out the pcv valve, sprayed it in there, let it soak, then used a compressor with a spray nosel and sprayed air in there as much as I could, a day or two later after that is when the first af code came up. I wonder if I broke some stuff lose and it's stuck in the combustion chamber or something., I think what I'm going to do is put about 3 or 4 cans of seafoam in the tank, and try it in the intake a couple more times, if that doesn't work then I'll take to mechanic, I just hit 170k miles, I've already spent lots of money on it and everything is starting to go now, Im afraid my RX days are coming to and end. We'll see how it goes, it was a fun ride and this is a great community and I'm glad I got to be part of it for a while. Thanks to everyone.

Edit: also changed the spark plugs right before doing the seafoam, denso iridium