clyde1952

Needless to say, I am very disappointed but my lights have returned. They have come and gone 3 times since my last post... They stay on for a couple of days and go off for several days.. I apologize if I have mislead anyone for the repair.. I am convinced the problem is with the fuel tank vapor control system, but it seems to be getting better and better, therefore I am not concerned at this point.

clyde1952

Well,, I think I have finally found the problem. Found a cheap, yet very good OBD-II blue tooth reader for around $10 on ebay... This thing is very small, about 2"X1" and can be left in the socket while driving. You can get a free app called "torque" for an android phone and see a lot of things that are going on with your car while driving... It even allows you to graph points coming into the ECU in real time. While looking at several points, I notice the bank 2 sensor 2 oxygen sensor was swinging all over the graph. All the other sensors were very smooth on the graph and not fluctuating. I decided to replace the sensor and just see if it changed. After replacing the sensor, the graph was smooth and no more lights or codes... I have waited for a few weeks to make sure that I did not have another false fix... Everyone should get one of these readers.. I have installed them on both my cars and just left them... They as come with a windows based disk that will do what the android app does on the laptop...

Tom558

Something like this?

clyde1952

Yes,, but it is the smallest one.. on that page, it is a "super mini"

Rxlexus350

Hi,

I pretty much have the same issues as you did on my 2010 Lexus RX350.

I used the scanner and it says PO420 Catalyst System Efficiency Below Threshold Bank 1.

The lights on the dash are: Check Engine, VSC and the AWD.

Can you recommend the scanner you got on EBay and perhaps which sensor to replace?

Thanks in advance.

Shnewzhere

If you need to replace your catalytic converter, here is my journey to learn from.

Rxlexus350

Hello,


Based on the pic from the scanner, is this the sensor before the catalytic converter or after?

Mesquite77

So, the sensor before each bank's cat is an A/F Sensor and determines fuel trims. The sensor after each cat is an O2 sensor and determines how well the cat is doing its job.

Rxlexus350

Thanks for the reply! So based on the scanner, can you determine if it’s the front or back? Are you able to tell?