CaltonB

I now have the second knock sensor code on p0330 and p0325 for both banks and it says knock circuit on each. The Car also will not shift to fourth, high rpms and bad gas mileage. Does this basically mean change the sensors and harness? I've cleared the code a few times and it comes right back on.

salimshah

When you get an error, you are being informed that seething is wrong in the particular loop. Most likely it is the sensor and or the harness, but it can be the connector at the eco or wire in-between. The question is are gouging to do the diagnosis and the work or intend to go the mechanic.

Salim

CaltonB

I've been to a few mechanics at this point one wanted to changed the knock sensors at a high price right away... the second said the knock sensors tested normal and that it could be an issue with the lifters (they also said they were unequipped to do such labor on a car). Both did a "diagnosis" so I am not really getting a straight story here from someone. I guess my last option is to take it to the lexus dealership and have them diagnose it but I don't imagine them telling me anything other then change the knock sensors. From reading a lot of this forum and the issues this light has presented I don't want to pay big bucks to have the knock sensor and harness changed to have the codes reappear again. Are there any smaller maintainences that can be done before I jump to this? I still was thinking the car may need a tune up (spark plugs etc..) or would that show a separate code? I also hear that changing the fuel injectors was a possibility for a fix. The car is 140k miles so damage to the lifters seems a bit far fetched to me but maybe this is the case. The engine seems to be loud in general (not sure if it is exhaust or other vibration) and there is vibration when the car is idling in gear... I am not sure if this is motor mounts but I think they would have looked at that after the first two diagnosis's. Not sure if that can trigger two knock sensor lights either. I am a relatively new owner of this car so I am not exactly sure where to start.

fastnoypi

at this point the dealer has the most resources to troubleshoot and diagnose your issue, might be worth your time and money for them to look at it for peace of mind and knowing that things will be put back together "Lexus/Toyota spec"

CaltonB

Yea.. I guess it's time to get over my fear of the dealership. I hate that for about a hundred more of their diagnosis fee I can get the spark plugs changed but maybe I'm wrong in that regard.

salimshah

Spark plugs should have been changed at 110K (recommended) service. So even if it is not knock sensors, you should do this service.

From what I have observed, 140K for new knock sensors is about correct. These machines do need servicing and some can be expensive.

Salim

CaltonB

I have no problem replacing the knock sensors if that is the issue I just want to make sure that is actually the issue. The second mechanic I took it to was very thorough and I told him my concerns about it actually being the knock sensors and he said that he tested them for resistance and that they checked out fine. He also would not have a reason to lie to me as he could have easily said they were bad and given me the big bill to change them as they are equipped to do that job but instead he referred me to an engine specialist. Is it still possible they can be bad after such a test? I called again today to confirm and he said that the the ac compressor clutch putting strain on the engine (the clutch is sticking and making a loud noise) and a lifter noise was causing the two knock sensor codes.

salimshah

Just run without the AC.

I can't say with authority, but ohm check is a rudimentary check. Right check is scoping the signal output. I don't think you will get a definitive answer here. Go with the gut after eliminating all of the other possibilities one at a time.

Salim

CaltonB

Yea i've been limiting my ac use (it's 115 out here right now so kind of hard) but I don't think that's a huge contributor... I called the dealership and they essentially told me they would scan the code (which I already gave them), check bulletins and test drive the car to find out the source of the problem. There's another mech I know closer to my home base about 50 miles away who specializes in lexus. Is it safe to drive that far with the car unable to engage 4th gear? The rpms will be high in 3rd on the freeway which i'm guessing will shorten the transmission life and if this mechanic is right about the lifters possibly harm the engine as well?

marcov

HISTORY: I bought this 1999 RX300 three months ago from a friend. We previously changed both knock sensors (had a P0330). Since then I've changed both A/F sensors (had a P1133 & P1135). Chk.Eng. still on, It runs fine but will not always shift into overdrive.
NOW: Ran diagnostic (EB2) three times in the past month and I still have a P0330, P1133, P1135 "and" P0125 (Eng. Temp). The engine runs "extremely well" for a vehicle with high miles. Today I removed the computer (ECU), visually verified the inside components and all the connector pins and sockets and saw nothing unusual. I also removed and cleaned both Transmission speed sensors, and all engine compartment connectors including grounds! Reinstalled everything and went for a test ride, "check. engine" light came back on after about three miles...
My Question: Does anyone know what wire to either cut or ground or whatever to "bypass the signal that stops the transmission from going into overdrive????? I'm pretty sure all the codes are invalid and I don't want to buy another ECU......
Thanks.

salimshah

Before taking that step, why not visit a mechanic or use live streaming to see which sensor is saying what. You could be burning extra gas and indirectly loosing more money than what you would a mechanic.

Salim

Salim

maxSteel

I don't know what EB2 diagnostic is.

P1133 and P1135 are both for A/F Sensor B1S1
P0125 refers to B1S1 but says fix other codes first

Limp mode is trying to get you home without damaging the engine.

salimshah

I suspect EB2 ==> OBDII

Salim

marcov

Yes, OBD II. sorry about the misquote. I already changed both A/F sensors and both knock sensors.

marcov

I would just like to know how to override the computers decision to stop o/d gear from engaging, the vehicle runs "very well".