rmartindc

Hello,

I have a 2001 Lexus RX300 with 123,000 miles. I recently have been getting my check engine and VSC lights and when I read the codes I get code P1150 which is the Air/Fuel Ratio Sensor Bank 2 Sensor 1. I replaced that sensor which is located in front of the radiator with an OEM Denso 234-9009 part and have been seeing about a 2 mpg increase (still only getting 13 mpg city). However, after driving 20 miles my check engine and VSC lights came on with code P1150 again. I cleared the codes, drove another 20 or so miles again before both lights came on again and got the same P1150 code. The car did try to stall one time by idling low but that has not happened again.

Any idea why the check engine and VSC light come on and read code P1150 again?

Any help would be appreciated, thanks!

Nad1370

Did you buy the sensor at a reputable source?
There is a lot of "FAKE" AF sensors out there.
If you dont mind, how much did you pay for the sensor?

Also if you have a freeze frame data when the code set, post it here so we can decipher it.

rmartindc

I bought the sensor at my local autoparts store and it was about $180 for the original Denso part. Last night, the car also started getting code P1153. I am including a freeze frame data picture onto this posting too if it is any help.

Thank you!

abstractj

any update to this issue? I got the same code today and I just changed the sensor about a year ago. I can’t imagine it fail so fast?

Margate330

Ok plz don't laugh because I'm being serious for real.

This hapened to me too one time on my AF sensor that was less than a year old.

So, I pulled it for inspection and it had a tiny piece of what looked like rubbery gasket material from somewhere
on the engine stuck to the tip- how it got there I don't know, the engine somehow puked it out.

So, I flicked it off and sprayed it with brake cleaner if I remember correctly and reinstalled it.
The code went away and that was over a year ago- never seen that happen before and haven't since...

slothman

yes, any sensor can go bad, even after a month. However, it maybe the female/male connector do not have a solid clean connection. Pull the battery negative off. disconnect the wire. Clean both ends with electrical cleaner. Re-connect both ends, and make sure you hear the "click". That might fix the issue. If not, I would buy a new sensor. o2 sensors normally cannot be cleaned.

abstractj

Thank you. I will take the O2 Sensor out to check it + test it with the multimeter today to ensure that it's failing.
I did a freeze frame reading and got the following:
FuelSysA CL
FuleSysB CL_Fault
Load_PCT 46.7%
ECT 176F
ShrtFT1 1.6%
LongFT1 23.4%
ShrFT2 -1.6%
LongFT2 32%
RMP 1850
VSS 19mph
IAT 100F

Looks like both of my Long Term Fuel values are high. In reading and understanding that that means here are some possible scenarios:
1. vacuum leak
2. MAF sensor that's reading the amount of passing air wrong or possible due to a vacuum leak
3. Clogged fuel injectors
4. Bad O2 Sensor

I'll check for #2 and #4 today and see what happens. Just sharing the info so future members can reference.

slothman

also, usually if you have a vac leak, the motor will rev higher at idle once the motor is warm.

Margate330

Thank you for posting the live data.
Yeah, you are not going into closed loop as you already know at "FuleSysB CL_Fault" so digging thru the manual I think this goes with bank 2 best I can tell- if I'm wrong about that let me know since had a hard time confirming it 100%.

Also noticing your fuel trims on both banks are sky high but bank 2 is an extra +10 worse than bank 1 so wondering if it's a fault with the AF sensor or if the fuel trims are just sooo bad on that bank due to other reasons it's throwing the AF sensor fault and keeping from going into closed loop.

Tough one since you just replaced the sensor a year ago and that's what makes it hard to decide which direction to go but knowing 100% the sensor is good first before chasing ghosts it what I would do but yeah it's a head scratcher...

Yeah, like mentioned above, I'm thinking if a vacuum leak it would be most obvious at idle but you are at almost 2k rpms and driving 19mph, engine up to temp too.
Bottom line, whatever is going on your fuel trims are horrible on both banks and I'm posting some thoughts so don't shoot me if I guessed wrong... lol

I like this one.

abstractj

I appreciate for your response and the video link. I'm not surprised if the sensor is bad. The bank 2 is notorious for failing even after a few months. It should be a breeze to take out and check. Waiting for the engine to cool down enough to check.

abstractj

I replaced the o2 sensor and everything worked fine until today. Now, I'm getting pending P1130 (bank 1 sensor 1) with current P0301, P0303, P0305 (all in the back area -ugh) I just had the coils and spark plugs replaced at a shop with Denso and new plugs. Going to take out one of the spark plug to see what kind it was used. The money pit continues...

Margate330

Hi abstractj, if your fuel trims are still sky high like posted above and you want fast answers you can buy a vacuum gauge at harbor freight for only $15 and know today if you have a major vacuum leak causing your misfire and codes.

If you can rule out a vacuum leak the problem may be electrical or fuel delivery related but vacuum is easiest place to start and give a direction for the diagnosis!

Add- need to see live scanner at idle with engine fully warmed up with vacuum gauge data based on what you posted above.

abstractj

Thank you for responding, I do appreciate it. Here is an update:
The misfires are intermittent for now. The P03xx codes went away after the engine cooled the next day. However, after driving on the freeway it came back and RPM was high when going 60 MPH. There are also intermittent rough idle, but it's not to the point where I feel the car may stall. Also, happens more on cold start, it then goes away, but comes back on after driving for a while (about 5 miles). No pending codes for now, but I haven't taken on the freeway or long drives after that initial incident.

I may stop by AutoZone this week to borrow their fuel pump diagnostic kit and test it. I've never done one before... I was looking at the diagram from another post:
https://cimg8.ibsrv.net/gimg/www.clu...16ceb7bceb.png

Are those the lines that I should be testing on my RX300? Are there articles or information on reading levels so I know it's off?
Thanks again.

Margate330

To diagnose high fuel trims at idle a vacuum gauge is best- not fuel pressure gauge.
This will tell you instantly if there is a vacuum leak even if you can't find it with a smoke machine.
Add- when starting the card cold it should read in the Green and as the car warms up it should climb up to approx 21, high in the Green on the gauge.

Only $15 at Harbor Freight and normally a stock item.

abstractj

Thanks. I'll have to make my way to HF this week. It's good to know the gauge is already set to certain specs and easy to understand.