rjacket

Does anybody know whether the smog sensor deterioriates over time? Firstly, yes mine is on the most sensitive setting.

Essentially, after my 15k service (when they clean the cabin air filter) the sensitivity seemed to reduce and I often get smog in the cabin now. There seems to be quite a delay before it notices the smog.

I changed the cabin air filter but it didn't seem to alter anything.

Any thoughts? It's one of those things that I'm sure the dealer won't fix because it's so hard to reproduce.

BinaryJay

To be honest I've never ever seen mine actually turn on by itself. I have no idea if it even works or maybe the air up here is just so clear that it's never "polluted" enough to trip it.

I don't really get what it turning on is supposed to do though, there is only one cabin air filter... when that smog light is off, isn't it still circulating through the cabin filter regardless?

rjacket

When the circulate option is set to auto, then the smog sensor is active and able to change between external and internal air based on the quality of external air.

Both internal and external air go through the same filter, it's just a question of when it's internal and when it's external. Filters don't capture everything, hence the need to switch to internal air when the external air quality falls below a certain level.

rjacket

Looks like the LS430 folks were having this issue. Here is a nice write up of how to clean it up. They should really put this in the maintenance instructions:

https://www.clublexus.com/forums/ls4...-cleaning.html

BinaryJay

Oh I thought that separate button with the filter on it had something to do with the smog sensor... the micro filtration thing. Is THAT something separate from the regular cabin filter? If I press it, it goes green... but I really don't know what the car is doing differently and I've never really felt the need to use it.

In the photo below, the little sitting man button:


As for your link, I guess add that to the long list of stupid little maintenance items that nobody tells you about and nobody performs for you when you take the car in. I'd be curious to see what condition other folks' are in if they ever yank it from their GS. I wonder if it would be safe to use electrical contact cleaner on that whole thing (like cleaning an MAF).

rjacket

Yes I thought that you were confusing the two buttons.

So the "man" button on the left forces your system into recirculating mode (although sometimes it actually changes it to outside air mode for some reason) and changes the airflow to the upper vents and puts them on a higher speed.

This goes through exactly the same system as your regular system. Nothing is seperate. The purpose of it is to spend 3 or so minutes cleaning your internal air quickly through the cabin air filter. I find it useful when I start feeling the effects of pollen (and now also to clean the internal air when the sensor has failed to shut off quickly enough). In fact, the Lexus / Toyota design is good because internal air goes through the filter. In some other cars only external air goes through the filter.

The auto button on the right allows the smog sensor to control whether internal or external air is circulated through the system including through the one and only cabin air filter.

BinaryJay

Thanks for the explanation. I did read the manual when I got the car but I guess I didn't quite absorb this properly. I've never really felt the need to press that button as I'm not very sensitive to allergens. I guess I'll try clicking it for giggles next time.

I don't suppose it does any good for farts, though I do find it fun to turn on the seat ventilation when I feel a good one coming on with the missus in the car.

By the way you mentioned that they clean the filter? I thought that filter was just a replace item, and not cleanable?

rjacket

A good air filter will deal with smells, so when you feel a good one coming, you may want to turn off the system altogether.

GS350 cabin air filter is cleaned at 15k, 45k etc etc and replaced at 30k, 60k etc etc

I just do it myself now. My 15k service was comp'd so they cleaned it.

rjacket

So here is the info. I haven't done this yet but will asap:

Location of GS350 smog sensor courtesy of twylie:

Passengers side near the outside of the grille opening. It sits to the outside of the horn on that side. Shine a flashlight through the grille on that side near the top and it's right there. Shape and size (likely same part) identical to the images seen here. I just looked in the service manual and went out to the garage to check. Will check mine this weekend as well.

Post he refers to where slvr surfr cleaned it on the LS430

https://www.clublexus.com/forums/ls4...-cleaning.html

twylie

iTrader: (3)

pics of it. Images aren't great due to a cheap point and shoot, but you can make it out pretty well here.

Mine is a 430, but the service manual shows the same plug and location on all engine variants.

rjacket

So once I purchased a ratchet wrench and socket set, it was all straightforward. Some tips for those trying it.

1) Ratchet wrench and socket is the only way to remove the sensor

2) You can press down on the electrical connector to remove it from the sensor. Wiggle it and it comes out. It is a firm fit

3) The sensor comes apart quite easily with a screwdriver if you press down inside the snap on connectors

Mine was nowhere near as dirty as the pics on the LS forum. I vac'd it thoroughly, the filter and the housing and blew off anything I could see in the crevices.

I also vac'd the sensor itself. It seemed to have a discoloration on it. It appears that the dirt was attracted to the actual sensor more than any other part of the sensor housing. So while overall the sensor housing didn't look very dirty, perhaps dirt had gotten into the sensor itself and reduced it's ability to sense smog. So I hope applying a strong vac to it has cleaned it out if that is the issue.

In any case, I will take the car out soon and see how it reacts.

rjacket

So two weeks in and smog sensor clean seems to have done the trick.

I had the (mis?)fortune of being behind a couple of diesel trucks that decided to suddenly accelerate and put out huge puffs of black smoke. The first time it didn't turn on but nothing came into the cabin anyway (must have been that clean diesel they talk about!). Second time it came on and nothing came into the cabin.

I drive with confidence now!

bud13

I have a 04 430/UL and I don't see the filter anywhere on the bracket in front of the radiator as shown by the other pictures. The only thing on there are the two horns and the hood closing stuff. I wonder where it could be located?

aznxenon

Thanks for bringing this back from the dead, we're on our 4th Lexus for over 13 years and this is the first time I've heard of the smog sensor.

Will clean it this weekend