Smog Sensor Doesn't Work When Cold?
 

First, I have to say that the automatic smog sensor that recirculates the air is one of those little features that I now wonder how I lived without. In my old ES, I was constantly on the lookout for buses and trucks spewing all sorts of crap into the air, ready to stab the recirculate button. (I can't stand that sickly sweet smell of unburned diesel fuel, among other nasty road fumes.)

I noticed last week that the sensor was asleep at the switch, as I gulped some stench from a poorly-maintained school bus several cars ahead of me. I set the sensor's sensitivity higher, figuring that would do it.

Today, I got another cabin-full of stink. The only thing I can think of here is that it's been really cold here, and maybe the sensor just stops working if it's too cold. I found in the owner's manual that the air conditioner may not work at freezing temps. I'm thinking that this could be, in the parlance of Lexus technicians, an "operating characteristic" of the car. Does anyone else have a similar experience?

Yes, I think I recall something like that being discussed before and it may be something to do with preventing the windows from fogging up in cold weather.

Dave Mac

I believe you're right. It appears that keeping the windows clear takes precedence over the cabin air quality. Once again, it's Lexus engineers being a little too clever.

It's a great car, but its nanny "features" are really annoying!

It could also be that you have salt/sand/grit built up on the smog sensor as a result of winter driving. The sensor is mounted behind the grill, in front of the radiator. The hole in the sensor for air to enter appears to be on its rear side, likely to reduce clogging. Still, it couldn't hurt to hit it with a stream of water from a hose or run the car through a car wash and see if it improves.

Climate control in ES350 really has a mind of its own, and it often seems to me it is not completely sane.

AC coming on in relatively cool weather - what for? Just blowing outside air would be enough, AC gives that wet dusty smell to the air.
And if you force AC off, then auto recirculation turns off too.
Auto recirculation - I still cannot figure it out. I played with sensitivity setting, but still cannot get it to work properly.
Probably really need to get the sensor checked.
On cold mornings it takes way too long for the heater to kick in, you really don't need the engine to get warmed up all the way to get warm air coming.

I wonder if there was a firmware update that takes care of all the quirks?

The AC comes on in cool weather to reduce fogged windows inside & to keep interior temp from going above set point when in recirc mode.

The recirc shutting off after the climate system is turned off and then on drives me crazy too. It doesn't occur all the time, which is odd.

I have the smog sensor sensitivity set all the way up on mine. It works great at flipping to recirc mode automatically when a polluter pulls in front of my car. It doesn't seem to detect Diesel fumes from trucks/busses, but works well on conventional cars belching fumes in my face.

I haven't heard of any firmware updates to the climate control system.

If your heater takes too long to warm up, your heater core may be clogged. My car had the white powder problem (spews white dust onto dash when AC running), necessitating replacement of the AC condenser core. The mechanic replaced the heater core at the same time, since he noted it was clogged with white powder, too.

A-ha! That's what I noticed too - thick black diesel smoke would do nothing for auto recirculation. I am curious now how it would react to the stench from the cattle feedlot that I sometimes pass by? :D