tooslick4u

Hi everybody,

I have an 06 with 104k miles. Every time I have the a/c on with the fresh air/recirculate setting on auto, the system is always on recirculate. I've changed the sensitivity from its original position in the middle to Hi drove it a couple of days, changed it to Low and drove with that setting a couple of days, cleaned the filter inside of the smog sensor, and finally changed the filter inside. Nothing seems to every change it to use outside air. The system used to flip between outside and recirculate when driving around town.

I just want to know what you guys think could be wrong before going to the dealer and them charging me a diagnostic fee just to look at it since I don't have any other service that needs to be done.

Thanks in advance! This forum has been super helpful thus far!

Lavrishevo

iTrader: (1)

I would not pay the dealer anything. Their going to charge you $100 and tell you to replace the sensor. I would just buy one from Lexus of South Atlanta online or Sewell.

http://www.lexussouthatlantaparts.co...889850031.html

jimbosr1

mine does the same thing as yours,havent troubleshot it yet,if you find out what it is please post it.good luck

tooslick4u

Yea, I definitely don't want to go to the dealer if I don't have to. Will replacing the sensor solve the problem? I don't want to buy the sensor if its not going to fix the problem. Lavrishevo, did you have the same experience and replacing it fixed it?

jimbosr1

i am going to order a sensor tonight,we will see!

jimbosr1

just ordered it,shipping is $18.25
$122 total

jayclapp

Have you tried disconnecting the lead at the sensor and seeing if that make a difference. If it doesn't, that might indicate that the sensor is bad. Or you could ask your service advisor for his opinion. He might be able to point you in the right direction.

KawiLex

My sensor works well after I cleaned the filter and housing out. I couldn't drop a hundy on that if it didn't work... but I'm sure glad it does

Jabberwock

The sensor is an item that can be replaced and tested in 5 minutes. Just make sure there is a good return policy on the part in case it does not fix the problem.

aypues

mine is doing this too. I just accepted it and figured it's actually better because whenever it went from fresh to recirculate it got a lot colder and I was going up and down on the temperature whenever it switched modes.

how hard is the install on the new sensor??

jimbosr1

its just one bolt,10mm takes less then a minute to change.

jimbosr1

update: received sensor, installed and works as new.

tooslick4u

Finally gotten around to replacing the sensor. All is working again. Yay!

Hagar

Just one more thing to do.

I'm still learning things about this Lexus LS430 and have always wondered why "AUTO" seems to work only in recirc mode.

And now I discovery its suppose to show "AUTO" in fresh air as well?!

So I cleaned mine and no change. I disconnected it and no change. Not sure if that's a proper troubleshooting method or not. I tried the low setting as well as the high setting and it just sits there in recirc/auto

AND IF I need to replace it, there's one on ebay from a 2014 LS460 that looks exactly the same except for two #s for $37 free shipping. DENSO 013650-0010 and the 2014 is Denso 013650-0050

StanVanDam

The smog sensor is checked as follows:
1) TechStream - enter the A/C System ECU, check the Data List. If DTC B1418 is there, A/C ECU likely needs replacement.
2) With the A/C ECU's connectors still connected, turn ignition ON, wait 30 seconds, then check voltage between terminals DGS (+) and SG-1 (-). Voltage should be 1.0-4.5V at 10-35C (50-95F). When the sensor is exposed to exhaust gases, the voltage should go down.
3) Unplug the smog sensor, apply battery voltage (12V) across pins 3 (+) and 5 (-). After 30 seconds, measure the resistance across pins 1 and 2. Resistance should be 5-100kOhms at 10-35C (50-95F).
4) Check harness between A/C ECU and smog sensor
5) Failing all of that, replace the A/C ECU

General AC system diagnostics (to check air inlet system):
To enter AC diagnostic mode, hold down the AUTO and RECIRC/FRESH AIR switches. Without pressing any buttons, the system enters a continuous sensor check operation. The trouble codes will be displayed where your driver side temperature setting normally shows.

To change to a stepped sensor check operation, press the UP driver side temp control switch.

To change to the continuous actuator check operation, press the RECIRC/FRESH button once. Then to change to the stepped check operation, press the UP driver side temperature switch to cycle through the checks.

There are 10 steps, 0 through 9. Steps 0-3 (first 4 steps) set the air inlet damper to FRESH. Step 4 (fifth step) is RECIRC, and steps 5 through 9 are FRESH.

Press OFF to exit the diagnostic mode.

If you don't shine a bright light on your front and rear solar sensors, you will likely get DTC 21, 24, 28 (B1421, B1424, B1428). You can ignore those.

A problem with the air inlet damper position sensor circuit = DTC 32 (B1432)
A problem with the air inlet damper control servomotor = DTC 42 (B1442)
A problem with the exhaust gas sensor circuit = DTC 61 (B1461)

If you have TechStream, check the AC system options. AIR INLET MODE should be set to AUTO instead of MANUAL, and AIR INLET OPERATION should be set to LINK instead of NORMAL

Also, perhaps reduce the sensitivity of your smog sensor. With the ignition ON, hold the RECIRC/FRESH button for 5-10 seconds and the screen will change to let you select 7 sensitivity levels. I keep mine on maximum because I want the least amount of vehicle exhaust entering the car, and it works good as new. I cleaned my smog sensor once, several years ago. It seems to use some kind of heating element that requires a 30 second warmup time, so perhaps cleaning it every 2-4 years will prevent excessive grime from burning into it.

Some background reading:

In the LS400 automatic air conditioner system, the ECU determined the required outlet air temperature and blower air volume in accordance with the calculation formula that has been obtained based on information received from the sensors.

However, because the senses of a person are rather complex, a given temperature is sensed differently, depending on the environment in which the person is situated. For example, a given amount of solar radiation can feel comfortably warm in a cold climate, or extremely uncomfortable in a hot climate. Therefore, as a technique for effecting a higher level of control, a neural network* has been adopted in the LS430's automatic air conditioner system. With this technique, the data that has been fetched under varying environmental conditions is stored in the ECU, which effects control to provide enhanced air conditioner comfort.

*: Neural Network = Is capable of effecting complex control by artificially simulating the information processing method of the nervous system of living organisms in order to establish a complex input/output relationship that is similar to a human brain. The neural network control consists of neurons in the input layer, intermediate layer, and output layer. The input layer neurons process the input data of the outside temperature, the amount of sunlight, and the room temperature based on the outputs of the switches and sensors, and output them to the intermediate layer neurons. Based on this data, the intermediate layer neurons adjust the strength of the links among the neurons. The sum of these is then calculated by the output layer neurons in the form of the required outlet temperature, solar correction, target airflow volume, and outlet mode control volume. Accordingly, the air conditioner ECU controls the servo motors and blower motors in accordance with the control volumes that have been calculated by the neural network control

Normal Operation
* When the air inlet mode is selected in the automatic mode, the air conditioner ECU automatically switches the air inlet to the recirculation mode or to the fresh air mode by making a comprehensive analysis for preventing the intrusion of the harmful elements (CO, HC, NOx) that are present in the exhaust gases that are contained in the air outside of the vehicle, thus ensuring the maximum cooling performance in the summer and preventing the fogging of the windows in the winter. Also, when the automatic mode is selected, the air conditioner ECU automatically turns ON the compressor. However, to allow for the smog ventilation sensor to warm up, the automatic switching of the air inlet modes through the detection of the elements is not carried out for 30 seconds immediately after the engine is started.

Automatic Internal Air Cool Down Operation
* When the air inlet mode is in the automatic mode and the vehicle’s internal air temperature is high, such as in summer, the air conditioner ECU switches the air inlet mode to the recirculation mode in order to reduce the internal air temperature.

Automatic External Air Fogging Prevention Operation
* When the air inlet mode is in the automatic mode and the blower or the compressor is turned OFF through the manual operation of the switch or through automatic control, the air conditioner ECU switches the air inlet mode to the fresh air mode.

* When the outside air temperature is low, the air conditioner ECU automatically switches the air inlet mode to the fresh air mode in order to ensure the defogging performance of the window.

NOTE:
* The smog ventilation sensor cannot detect elements such as the smoke from a bonfire or factory exhaust, foul or animal odors, and dirt or dust particles. Therefore, the air inlet modes are not switched in accordance with those elements.

* Depending on the direction of the wind, the smog ventilation sensor might not be able to detect the exhaust gas elements, and could emit an odor.