I have had a CEL and VSC / VSC OFF lights on for about 3 months now. I went to the shop about 2 1/2 Months ago and they said that it was an oxygen sensor and wasn't an urgent problem. I have recently noticed a lot of sluggish and hesitation in my acceleration, especially when rpms get up. I went and had the codes read at autozone and it came back with:

P0031 Heater Control Heated oxygen sensor Bank1 Sensor1
and
P0325 Knock Sensor 1 Bank1

I am getting an estimate on the Knock sensor, but was wondering if I could do the oxygen sensor myself. I am not a mechanic by any stretch but and somewhat handy. Can anyone help me as far as if these sensor codes seem to fit the proplems in performance of my car, and help me with how to replace the oxygen sensor. Also anyone have a part number for the oxygen sensor? I would hate to get the wrong one.

Thanks and sorry for rambling!

2003 Lexus GS300
145k Miles

 

Denso's part catalog lists two different O2 sensors for the upstream and downstream sensors on the GS300 (why I don't know). I'm not sure, but you're probably looking for the upstream sensors (there are 2) and they are very easy to replace. I think the sensors are 17mm sockets and once you take the engine cover off and find the sensor on the manifold, remove the wire harness plug and unbolt it you might be in for 20 mins of time. Very easy. Don't know if you need to, but I'd disconnect the positive battery cable while you're doing this.

http://www.densoaftermarket.com/catalog/
The two p/n's are below, they about $55 each on Amazon.
234-4630
234-4048

 

There's also this thread, which I found in the stickied help thread
https://www.clublexus.com/forums/per...placement.html

 

Actually I think its a 22mm wrench for the O2 sensors or a 02 sensor socket will work.

 

I know this might be asking a lot but is there any way someone has a picture or diagram of exactly where the Bank 1 Sensor 1 oxygen sensor is located on a 2003 GS300.. I just need to make sure i am removing the correct one. It looks like I should be able to get to it by just reaching down and unscrewing it. Is that not a possibility? Thanks for the Help!

 

Your car has 2 cats. The cat that is the nearest to the radiator is bank 1. And the oxygen sensor 1 is also the one nearest to the radiator. Sorry for bad analogy

 

Just replace the oxygen sensor and still have the VSC and VSC OFF and CEL light on. Does that mean it must be the knock sensor, since the oxygen and knock sensor codes were the two that came up

 

did you even cleared the code? the only way it would clear up by itself is after you have done a 40 warm up cycle trip.

 

I disconnected the battery for 30 min. I thought that would clear them. Is that not the case? I am still getting the VSC, VSC OFF, and CEL light on. As soon as those light come on I start to get the occassional lag and hesitation in acceleration... almost like my car is going to die for half a second.
Here is a list of what I have had done/ replaced myself in the past week.

Denso Oxygen Sensor Bank1 Sensor1
Spark Plugs (Denso Iridium Power)
Cleaned the MAF Sensor and Throttle Body
Cabin air filter
Engine air filter
Seafoam in Gas Tank
Marvel Mystery Oil


The oxygen sensor doesn't show up anymore, but I am still getting the Knock Sensor 1 Bank1 P0325 Code.

Car runs a lot better/ more power with new plugs.

I am just wondering how big of a job it is to replace the knock sensor myself and does anyone have a diy... Thanks so much. Hoping fixing the knock sensor will do the trick with hesitation issue.

 

disconnecting the battery will not clear codes on an OBDII car. You will need to clear the code with an OBDII scanner or do what the previous person said and wait for a while until the computer recognizes the correction made and clear itself

 

If you cleaned the Maf, you probably killed it. Those things are very sensitive. From experience and from other users, once they clean the MAF, the maf usually becomes faulty. Search the forums. I actually replaced the Maf, and car gained all its lost horsepower again. The sluggishness also went away.

 

What did you use to clean the MAF? ^ is right, MAF Sensors are very sensitive. Hopefully you used a MAF sensor cleaner and not anything else. Before you spend more $, I would suggest checking with your local auto parts store to see if they will let you borrow or rent an OBDII scanner and clear the codes and see if they come back. Or go and buy one, they are fairly inexpensive (here is one on Amazon for $21.39). Good luck!

 

Yea, you can't really damage the Hot Wire unless you touch it physically or use the wrong cleaner such as brake cleaner. Only use CRC Mass AIr Flow Sensor Cleaner or an electrical parts cleaner that doesnt leave a residue behind. Im relating this to the 2GS only.

 

I don't know. But if you search my threads, you will see that CRC Mas cleaner did not work for me. I didn't have any codes for it, it was working fine. We testing it in my friends GS, didn't feel any diff. Put his Maf into my car, and felt and improvement. Ordered myself a new Maf, and my car became a rocket. Wheels peel out no problem. Changed everything. And I have a nice OBD2 scanner, so all codes, and even cpu were reset completely every time. My friend ended up getting a maf from a local parts store by the way. No diff in his car. He ended up buying one from Lexus, and his car improved in the pep dept as well.

Oh, he cleaned his Maf with CRC cleaner as well. So I don't know. What I do know, is that I won't be using that on my Maf anymore for sure.