I have adjusted all the tires and reset the warning twice. It is OK for about 3 weeks and then comes back on and the pressures have NOT changed. Can the sensors that measure the wheel rotation get dirty ?

 

How old are the sensors. Checking pressure when tires are cold?

 

The age is the age of the car. Lexus LS 430 does NOT use the in tire battery powered sensors. Instead it measures the RPM of the wheels and compares them if one is too fast (low pressure=smaller diameter=trying to keep up=higher RPM) it indicates an error. That is why it doesnt tell you which one. Also because of this method, it doesnt matter when you set the pressures as long as they are all set at the same time and the same pressure. Low or high doesnt matter as long as the tire diameter is the same, Cant use different size tires.

 

Well, if you're adventurous, you could jack up each corner of the car and measure the diameter of each tire when inflated correctly. You may find the tires to be different enough to cause the fault. The WSS for the ABS system is also used for TPMS, so if there was a fault in the sensor, I would think it would show up as an ABS fault as well..

Or, disconnect the battery and let the whole system reset...

 

Not having any ABS errors, I guess I will try the disconnect. I just dont understand why it will be fine for a month then give a fault.

 

Jimisbell....I had the same issue. My problem I believe is that my tires had different tread wear. I had the dealership try to pair the tires with similar tread wear on the front and back. For example; the tires with the lowest tread wear were on the front and the ones on the highest tread wear were on the back. I believe that solved the issue for me. If this happens to be your issue, when rotating the tires don't do a full rotation. Just rotate the left front with the right front and vice versa for the back. One last note, I am not sure of this, but when the tire pressure light is on, I believe it throws of the number of miles left before your car runs out of gas. I was driving around with the light on and the on board calculator said I had something like 50 miles left....not. Nothing like running out of gas on the said of the highway in Oklahoma.

 

Are you just reseting the TPS or are you initializing? I had similar issues but once I did a full calibration, I never had a problem with the light coming on.

To do a full reset, you need to turn the ignition to on, and then press and hold the reset button for about 10 secs. This will re-calibrate/initialize your sensors, just make sure you have the proper psi.

 

Sorry.. this reset does not work for me on the low tire pressure ideiot light..
Is it the Reset button on the steering column?

 

It should't be called reset button. This button sets threshold psi. Once all your tires cold psi is at recommended reading and if you want to set the threshold there, then hit the button. From the beginning, once it is set, you don't need to touch the button again. ever unless you want to change the threshold. And register the new set of TPMS into ECU. There is no reason warning light should come on.

I have two sets of tires/rims for summer and winter. psi setting for summer tires are recommended 33 psi winter ones are at 36 psi. Cold weather drops this to 33 psi.
I never touched this button since the vehicle was new. When I switch tires/rims I just register new set of TPMS into ECU. For this I use handy Autel TPMS scanner/reader which will read all TPMS status(ids., psi, temp. battery status), then I connect it to OBD II port, I just issue relarn command which will register just aquired TPMS ids.

 

Not sure where you're located but there are no TPMS sensors in the LS430 tires. At least here in the US. The computer calculates each tires rotation using the tone ring from the ABS system.

 

Dave, please give these procedures a try...

 

Now I got it. I have one Bimmer in my family works like that. No TPMS on the rims. In this case you inflate tires to recommended psi, then reset it using iDrive.
Anyyhing on the owner's manual for your vehicle?

 

Thanks! I'll give it a shot.... will let you know!
Thanks for your time!

 

I am certainly a dummy but... where is this switch?
"With Multi–Display: Press and hold the Tire Pressure Warning switch until “Pressure Initial” appears on the Multi–Display."
Help!!

 

The switch is located on the underside of the dashboard, just above your right knee while you're seated in the driver seat. You will have to get your head under the steering wheel and then look upward to find it.