The only difference I noticed was a drop in RPMs while idling after the engine had completely warmed up. However, I was more suspect of the O2 sensor causing this (codes p1155 & p1150). The a/f sensor was replaced this morning so I should know more after I drive it tonight.

 

Just curious, as I have had the same lights on, same codes showing, along with a couple others, and there is no difference in the vehicles' performance. I have let it go for 3 months now and I drive 500 miles per week. Gas mileage has even gone up 1.5 mpg since I put new tires on recently.
I have seen dealers and members chasing these codes for years, dumping hundreds and eventualyy close to $1,000 into these RX's to "make the lights go away" and it seems to only be temporary, and the lights come back on. I'm hoping the lights burn out soon.

 

my lights have been on for a couple of years now. I just keep reseting them using the OBD scanner. I haven't seen any adverse affects - just the annoyance.

Which tires did you go with? Any feedback as I need a new set.

 

I just replaced both of my a/f sensors because of multiple codes on each one; there was also the PO125 that I understand may be derivative of the other codes.
With the new a/f sensors, all the codes are gone, including PO125.
No idea on your PO500 though.
Much thanks to the LexMex and 81corolla for their excellent posts on the subject.

 

New A/F sensor in and no CEL yet. I'll keep my fingers crossed.

Thanks all for the suggestions!

 

So its been a week and still no CEL.

 

I have the dreaded dash light problem: Trac, Check Eng, and VCS.
I scoured this thread but I didn't find the same code combinations.

I reset the codes by pulling the battery cable. Almost exactly 24 hours later, the lights were back on.

Here is what AutoZone showed:
P0171 - System too lean, bank 1 (cylinder 1)
P0300 - cylinder misfire detected (I assume that this one should be ignored)
P0305 - Cylinder 5 misfire
P0301 - Cylinder 1 misfire
P0303 - Cylinder 3 misfire
P0141 - Heates Oxygen Sensor - Bank 1 Sensor 2(H02S12) heater circuit malfunction


Autozone suggested an Oxygen Sensor ($109) and a coil ($170) for cylinder 1.


Any thoughts or ideas???

 

Welcome to the Club.

The ones I would focus on are 301, 303 and 305. Those are potentially 3 ignition coils on the back side of the engine block that are at issue.

Does the vehicle feel bogged down?

 

Hello Lexmex - thank you for the reply.

Yes, the vehicle does feel bogged down. It feels like there is no power, although the engine still sounds ok.

I have an O2 sensor, but I'm not sure that it's really the problem and it's an expensive part to just take a guess on. They ended up charging $180 for the part!
It was also suggested that I check the MAS, but I'm not sure that's really the problem either.

How do I determine which coil(s) are bad?
Is there a test that I can perform?




Thanks!

 

The bogging down is definitely the coils and it sounds like one or more are dead (sometimes they go out and then come back).

The trick we've been doing in this forum is to remove on or more of the coils in question (in this case, it's the 3 coils on the rear) and then put them on the front) and see if a different code comes up.

In this case
P0301- back, passenger side coil
P0303- back, center coil
P0305- back, driver's side coil

P0302- front, passenger side coil
P0304- front, center coil
P0306- front, driver's side coil

https://www.clublexus.com/forums/rx-...-patience.html

That link also shows the coils in question.

They're not cheap from my recollection, going close to $100 each and be sure to use the Denso coils (not some cheap non-Denso version).

 

Clever diagnostic trick.
Amazon seems to have the best prices, $66.00, http://www.amazon.com/s/ref=nb_sb_no....78_163&fsc=-1

 

Ok - the RX is beginning to get the best of me!

I took a chance and installed the O2 sensor (bank 1 Sensor 2). I also cleaned the MAS.

Then I reset the codes and took it for a spin. Every thing was great - no lights and full power. Then - the indicator lights came back on.
Back to AutoZone for the codes. This time I had only 1 code: P0141 - the code for the O2 sensor that I just replaced!
So, I rest the codes again in case I didn't let the caps discharge long enought the first time. Drove the car for about 40 miles and the lights came back on again. Checked the code again and it's P0141!


I'm beginning to wonder if I'm looking at the proper O2 sensor.
I've only been able to locate two of them on the vehicle: One in the front of the engine near the radiator and one on the exhaust pipe before the Cat.
I replaced the sensor on the exhaust pipe before the Cat.

I found this nice diagram (attached) showing the location of all potential O2 sensors and it appears that I replaced the correct one.
However, this diagram kind of bothers me - it shows Bank 1 Sensor 1 on cylinders 2, 4, 6. Shouldn't this be bank 2?
And, it shows Bank 2 Sensor 1 on cylinders 1, 3, 5. Shouldn't this be bank 1?



Tomorrow I'm going to attack the connections, clean them, and follow the wires looking for any obvious problems.


Regarding the previous misfire codes - I'm assuming that either the MAS cleaning or the new O2 sensor addressed that issue. Especially since I seem to have full power again.



Any thoughts on this???


Thanks!

 

Bank 1, Sensor 2 (sensor related to P0141 code) is located after the cat below the vehicle. Diagram above is for another vehicle, not the 1MZFE motor. In addition, bank 1 sensor 1 in the RX300 is behind the engine block, and bank 2, sensor 1 is closest to the radiator.

 

Thanks Lexmex. What you are saying and showed on your picture makes a whole lot more sense to me than what the guys at AutoZone and their drawing showed.

I crawled under the car this morning, and sure enough, the sensor is right where your picture shows it.

Now it's back to AutoZone to have a conversation with them on why they gave me the wrong sensor and what they are going to do about it.

I'll let you know how it goes.

Thanks!

 

Luthr, can you be so kind to edit/remove the picture so that other members are not mislead.

Salim