P0330 Question, Knock Sensors

[Tarheel72]

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

[Tarheel72]

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.

[jaswood]

"..not long after getting a fill up..."

CLUE.

Top off with preminum.

Knock sensor failure is unlikely, more likely engine actually knocking during acceleration.

[Tarheel72]

Thanks. But would you get the same code for knocking as you would get for knock sensor failure? I assume if you have a sensor it must notify you if the engine is knocking but wouldn't that be an entirely different code? I can't hear any engine knocking or pinging upon acceleration, but I will take your advice. The code reader says P0330 - "open or short circuit condition, poor electrical connection, faulty knock sensor"