My wife has a 2000 Lexus GS300. About a year and a half ago, the check engine light came on. I got the code read and it was an oxygen sensor...Bank #1 Sensor #2. Well several months back (she still has not gotten it fixed despite my many, many attempts) I had it checked again. Now two sensors showed up bad...Bank #1 Sensor #2 and also Bank #2 Sensor #2. I seem to recall reading on here or on a Lexus forum that one bad sensor can cause one of the others to show bad, even if the second is ok. I'm steering clear of the local Lexus dealership and was looking at having the work done at Limbaugh Toyota. I use them frequently and their service department is very good. The service manager told me that the harness for that back sensor (which I would assume would be Bank #2 Sensor #2) runs up into the car and connects under the back seat. Long and the short....well over $300 to replace the two sensors and I don't even know if both are bad or not. The $300 is just for labor because I've already bought both sensors online. What's your advice guys? I'm thinking of having them replace the first sensor, clear the code, and see if it comes back. Only problem with that is that it might not come back immediately and may do so an hour after I leave the joint and I've got a limited time table to get this work done to her car. Any help would be greatly appreciated. Thanks.

Matt

 

if you have the correct sensors, it is super easy to do it yourself, then unplug the battery to clear the ecl, and you should be fixed. now i have had problems getting plugs to match up with after market sensors from bosch. so make sure you have the correct plugs and sensors and it should be an easy swap. good luck

 

is the second sensor AFTER the cat on the lexus? if so, i wouldnt even replace it. if its like the 4runners, the front is the only one that effects the mpg and performance

 

I am not familair with the layout of the GS300 but both of the sensors you mentioned are after the converter and I would assume that car has (4) O2 sensors total since there is a Bank 1 and a Bank 2 (each bank will have a sensor before and after the cat). The sensor 1 or sensor 2 indicates if it is upstream or downstream of the converter, sensor 1 is before the cat and sensor 2 is after. It is more than likely that you can replace these yourself but again I am not sure of your skills nor am I familair with the layout of this particular car (a manual would be a very worthwhile investment if you are going the DIY route). Clearing the OBD codes is as easy as removing the negative battery terminal for a min or two before reconnecting.

It would be important to know what the actual code was as well:
P0136 O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)
P0137 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)
P0138 O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
P0140 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 2)
P0141 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

P0156 O2 Sensor Circuit Malfunction (Bank 2 Sensor 2)
P0157 O2 Sensor Circuit Low Voltage (Bank 2 Sensor 2)
P0158 O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)
P0159 O2 Sensor Circuit Slow Response (Bank 2 Sensor 2)
P0160 O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)
P0161 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)

You can see that there might be more than one reason for a sensor to indicate that it is bad and you'd want to know if something was causing them to go bad sooner than they should or just that both are just now "worn out".

 

I'm quite sure (although not positive) that both codes were O2 Sensor Heater Circuit Malfunction. I'm not going to tackle this myself, but I appreicate the feedback guys.

Matt