Jmai22

well went in today to my mechanic and to get my car plugged in to see why my engine check was on. well my EGR valve almost needs to be replaced and my O2 sensor was replaced today. dam the O2 sensor was 180 a piece from dealer. he charged me 150 for everything for 1 O2 sensor and the diagonistic. i'm gonna bring it back to him to change the EGR in a couple of weeks when i get more fund.

well my question is. what is the o2 sensor and how often does it go bad?

Seize

I had to change mine too, of course the car had over 120k on it when the check engine light came on indicating that there was something wrong. Glad it was the O2 and nothing else. Yeah it's quite costly, luckily for me I have a few friends who work at the dealership and they had one lying around.

Here's an excerpt from buyoxygensensors.com on what the main function of an O2 is:

An oxygen sensor is a measuring probe for determining the oxygen content of the exhaust gas. Since the amount of oxygen in the exhaust gas indicates precisely how complete the combustion of the air-fuel mixture in the cylinders is, it is also the best starting point for controlling the air-fuel ratio.

Regards,

-Seize

Rover

Jmai, what's up, bro.

Don't take your car to the dealer for the EGR, you can do it yourself.
I've had that problem a while back, here's the thread.
https://www.clublexus.com/forums/sho...ight=EGR+Valve
Good luck, bro.

marcus

Jmai.... Sorry to hear about your huge expense. I did a lot of searching 6 months ago and found that Bosch makes a generic O2 sensor that is designed to replace the Lexus sensor.... and .... it cost me less than $30 bucks. Sorry to add insult to injury!

Jmai22

wtf. 30 bucks. i'm using the Bosch O2 sensor that he had laying around. man thats soo gay. he charged me 150 for everything. i guess live and learn

indypwr

my engine lights hs bn "on" for a while and dont seems to come "off".........
ill just unplug the batter again in order to reset it. if it comes out again, ill make sure i get to see
my mechanic for diagnostic.....

007

Jmai22...i guess it is safe to say that you won't be taking it back to that guy for the EGR Valve since he charged you $150 for a $40 diagnostic and a $30 part... Sounds like $80 overcharge

Jmai22

oh yeah. well can someone confirm that the dealer 02 sensor is 180?? thats what he said. also how much is a new EGR valve. he said it is around 60 bucks or so.

also i did some research and i read that people were having a hard time removing the EGR valve. when i watch that guy do it all he did was bend the spring loaded arm back and unplug all the little hoses and it came out? am i looking at the right egr valve?

phollero

The spring loaded arms you saw are for the EGR Vacuum Modulator (black circular looking item with 3 vacuum lines at the top and one on the bottom. The EGR valve is to the right connected to the throttle body.

Anyone know how to remove the EGR valve for cleaning?

Soon2BVIP

I'm getting very bad gas mileage out of my Aristo, figure the O2 is a good place to start so going to be changing the O2 on it pretty quick here. Think that generic Bosch would work for the 2JZ-GTE? I'm only getting about 250-300KM's! per tank, so something's off.

94GS300

I am in the process of removing the EGR valve because of the code 71. It isn't too difficult except that you have to remove the EGR pipe too. The EGR pipe has 2 bolts very low in the engine compartment down by the exhaust manifold. I haven't been able to get a wrench on them yet. I am trying to figure out the best way to do that.

phollero

Attached is the part of the service manual that describes the inspection and removal of the EGR components. Page EC9 has instructions to remove the EGR valve. I haven't attempted it yet. If you do please let us know how it went.

94GS300

I have seen that part of the service manual. Those instructions are horrible. Removing the heater water valve helps a little bit, but removing the engine wire harness is damn near impossible.

However, I was able to finally get those 2 EGR pipe bolts out. You need to buy a long socket extension (15") and a swivel socket adapter so that you can reach them at an angle. It still isn't easy, but it worked.

There wasn't as much carbon in the EGR valve and pipe as I expected. I was getting the infamous "CODE 71" so I decided to clean out the EGR assembly. I was actually hoping to find a blockage in there but it looked fairly good. I cleaned it up and put it back on. I checked all of the other EGR components and they checked out fine. Took it for a test drive and the code 71 came back. So I have to look into this further. For some reason it seems like the EGR vacuum modulator is not modulating pressure correctly when installed. I took it out and it checked out fine. Seems like the exhaust backpressure is not getting to it. I need to put a gauge on there to see how much backpressure there is, but I am having trouble finding out how much exhaust backpressure there should be on that port. I haven't seen a spec for it.

Taking off the EGR valve and pipe was absolutely horrible. So anyone who is thinking about doing it, be prepared to spend many hours doing it!!

Maybe if I figure this out I will do a write up on all of this mess!

phollero

I'm in the same situation as you. In the service manual instructions it does not specify the vacuum pressure if you happen to have a gauge to test it (just says "low" pressure).

I have tried cleaning out the vacuum modulator as mentioned in post #8 of this thread which also describes how he fixed the code 71:
https://www.clublexus.com/forums/sho...d.php?t=237436

Cleaning the vacuum modulator did not work for me as my CEL came back on after resetting it. I was thinking of just replacing the vacuum modulator since cleaning it did not work. I wanted to clean out the EGR valve first to see if that would be the fix but it will probably be clean like yours. I don't want to go through all that effort if it's a long shot. Thanks for the feedback.

94GS300

OK - I just hooked up a vacuum gauge to the input of the EGR valve. I drove around with the gauge inside the car and I am definitely getting vacuum to the EGR valve so I know that the EGR modulator is working. I also know that the EGR valve is working by all my previous tests. I plan to drive to work with the gauge hooked up so that when the code appears I can make sure there is nothing wierd happening with the vacuum.

So either the pipe from the EGR valve to the intake is clogged or I have an intermittent short in my EGR temperature sensor. I really hope it isn't the pipe in the intake because that sure doesn't sound like fun either. I think it might be that pipe because when I give the EGR valve full vacuum at idle, the manuals say the engine should start running rough or stall. When I do it the engine just barely drops in idle speed. Nothing close to running rough or stalling, but I can definitely tell that it is making a difference. Has anyone else given the EGR full vacuum at idle? If so, did the engine really run rough or did it just kind of drop in speed a little bit?

I will keep everyone informed on my progress since it sounds like this is a pretty common and very annoying problem on these cars.