I have read some of the prior posts for this issue, but I have a few questions. My wifes car is a 2001 RX300 AWD. We have had the check engine light and VSC light on for about a month now. I got the codes read and they are P0171, P1130, P1153, P0174. I also brought it to a local shop and they said it's either the mass air flow sensor, or the O2 senor. Well I replaced the mass air flow, and 3 days later the light came on. I then bought one O2 sensor and replaced the front one for starters, and a day later the light came on again. Should I have replaced both of them? I know I should go back a get the code read again to see if any codes dropped and thats what im going to do tommorow, but I was curious if anyone had an ideas or could help with this issue. Also to throw a wrench into it, my catilytic converter sounds a bit more louder in the past few days, before I replaced anything. Could the sensors have caused any issues with this? I also found the clamp the connects from the manifold to the converter to be rusted and broke in half, I was thinking things might not be as tight and possibly some extra air could be entering? Kind of like a hole in a muffler? Im quite new at learning to fix my vechiles, so if anyone has any suggestions or could help me before I drive 2 hours away to the nearest Lexus dealership, it would be appreciated.

 

When you replaced the Air/fuel sensor was it a Denso or a Bosch....Bosch has given problems on this particular engine....Also any air leak will definetly false readings....You probably need a new gasket and clamp.... The sensor on the front of the engine on the exhaust manifold is a air/fuel sensor, though it looks like a o2 sensor....They are different.

 

did you have your airfilter changed recently? if so there is a vacuum line that plugs into the back of the air box. sometimes this line gets disconnected when the top of the air box is removed and doesn't get put on. it happens to mine all the time.

 

I have th evtc and check engine light on too. Happend today on my 01 rx300. Just turned 82k. Thought it might be a planned maintenance issue.
Does IBENTAB have a photo of the vaccuum line location? New to forum so please be patient if I am not following protocol- Thanks!

 

Definitely not planned maintenance. First thing to do is reset the light and see if it comes back. If it comes back, get the code read and let us know what it is. The guys on here can guild you to the right place.

 

Yeah that's exactly what happens when that hose is disconnected. I don't have a picture but if you look right behind the airbox you should see a hose or attachment that the hose should go to. again a lot of times it gets disconnected when someone changes the air filter.

 

I used a Bosch. I went back to Autozone, and had them reread the codes. To my suprise, the only codes that showed up here the two back ones. The front codes have disapeared. After getting under the car, I have found also why my car was a little louder, there is a piece that supports the pipe from the mainifold to the catilytic converter, that is attached to the frame. Well the weld from the support piece to the pipe has cracked and there is an exhaust leak. So im going to reweld it up and one fix that problem, but could this be also the reason why im getting these codes. On all the codes it said vacuum seal leak, before i spend another $180 for the second sensor, im going to see if this could be the fix. Ski2days, go to autozone and get the codes read, they do it for free, let me know what they are, and I will compare to my situation with you. Thanks all, and let me know what you all think.

 

Before you spend $180.00 at the local parts store check out Amazon.com and order a Denso, p/n 234-9009, for about $130.00 and have the original manufacturer part.

 

x2, it will be much cheaper to buy the OEM part (Denso) from Amazon than to buy from a parts store. That is if you don't mind waiting.

If you do buy from the local parts store do NOT get a BOSCH, these cars don't like them. It's like speaking a foreign language to someone that has no idea what you are saying.

 

That Denso 234-9009 I got on Amazon works like a charm, haven't had a single a/f sensor code despite having modified exhaust and intake, since I installed mine a short time ago.

 

So will the Bosch that I bought wear out soon? I also suppose since I installed it and it's been in for a week now, I can't replace it. Thanks for the info guys, so far, after rewelding the exhaust leak, the lights are still on, which I figured, but my wife hasn't complained. I was thinking I will have to replace the back sensor anyways. I appreciate the help from everyone who contributed.

 

Have you reset the lights after fixing the exhaust leak? If not, the sign is going to take a while to reset, as the computer needs to gather data before erasing the code by itself. If you want it erased you can pull the battery terminals for a few minutes, or pull the EFI fuse, or you can get a code reader and erase them.

 

I was reading down from the top and was going to suggest this very thing. I replaced my own air filter and managed to loosen the vacuum line. It eventually came off and caused the light. They hooked the computer to it and found the problem in seconds. Fixed it in the check in line and no charge . Light didn't come on again.

 

Hey IBENTAB and LEXMEX or any other experts. . On my 2002 the Check engine and VSC light came on again. 82k. Ruhns perfect.
After the first time this happend last week, I disconnected the the battery and the fuse you discribed. Lights went out. Came on agian today. Had scanned at AZ. Ist code says
P0446. In the LEXUS section of the readout it says "EVAP system vent control circuit. Probable cause 1.-open or shirt circuit condition. 2.-Poor electrical condition. 3.-Faulty vent Solenid."
2nd code says # P0440. (No specific list for lexus. )Unde BMW it says, "definition-Evap purge function plausibility. Explanation-Open or short circuit condition. Probable cause 1.- Poor elec. connetion.2. Faulty purge soleniod."
Under VOLKSWAGON it says "EVAP cannister pruge regualtor valve. Open or short dircuti condition. Probable cause- 1. Poor elec. connection. 2. Faulty canister purge solenoid. I do not find a loose vacuum hose and the gas cap is on tight.
What do you suggest from here. Thanks!

 

Charcoal canister in back is one that has come up for several members as a result of the codes mentioned. The other biggy would be a vapor pressure sensor, but just about every time this code continued for members (who wound up going to Lexus or some place that was big into servicing Toyota-Lexus vehicles), got the canister replaced (it's in a big black box underneath the rear of the vehicle).

How long ago was the code the previous time.