edbarrows

The TPMS light will flash for about 5 minutes, then turns on steady. I can reset it and the light turns off or after a while it will go out on its own. Then at some random time later, it will do this again. I've checked the tire pressures, they all read 38 (including the spare) with my gauge. The dealer said they checked everything and it all appears to be OK, they also "lowered the threshold pressure to 27". The TPMS light still comes on at random times. Anybody else have this problem and/or ideas on what to do to fix it?
I have a 2011 RX350 with about 11,000 miles on it. This started with about 9.000 miles and is continuing to turn on at intervals ranging from about 50 miles to 200 miles of steady driving.

Cruiter

I'd go back to the dealer again. You probably have a faulty TPMS sensor. On the 450h, they would be able to determine which one because you get 4 separate readings at the same time. But on the 350 when you only get a light if 'a' tire is low, they might have to replace them all. But definitely use your warranty.

GRPFAN

I hate those TPMS lights.

I never heard anything good about them.

Also, there should be a sensor for each tire to see watch one is the trouble.

I'd be temped to pull mine out when replacing my four tires.

Never had any problem with using a tire gauge once in awhile.

Geezzz were getting to lazy.
Hell we don't even have to turn our heads to back-up anymore in reverse

Evitzee

If you don't want the TPMS sensors in your tires you can always do a 'pipe bomb', making a pressurized canister out of pipe in which the sensors are placed and then pressure it up to 38psi or so. Just stick it in your trunk and you are set to go. Many on the IS forum go this route when they change to more exotic wheels which don't lend themselves to the sensors.

https://www.clublexus.com/forums/is-...pipe-bomb.html

BlueSurf

Early December I began to use 39lb in my 19" wheels. My 450 has the best mileage and the vehicle feels better. The ride is a bit harsher, however wear and mpg will much better. I had nitrogen, I found it to be nothing more than snake oil. Even with nitrogen you couldn't calibrate all tires to read the same pressure. Like air, its always 1-2 lbs and on occasion they all match up.

Cruiter

You'll likely have more than harshness with that much air. The center of your tires will soon start showing excessive wear and they're not cheap. Cost will be much more than a little more economy. Also with that much air, some early degradation of the tires strength may be possible.

The tire pressures printed on the door frame are what the Lexus engineers determined between Lexus and the tire manufactures to be the best for combination of ride, handling, mpg, and maximum tire wear.

UCSB

Just have the dealer repair the problem ... these sensors are an important safety feature in a rollover prone vehicle like the RX.

cafpaf

We have 18" tires and they are supposed to be set at 32 pounds. I don't really know, but could the TPMS come on because the pressure is high. Just a thought.

MC5Wes

The TPMS is a differential type system. All 5 tires need to set to the same pressure. Wether it be 20 or 40 psi.

If one tire is lower than the rest. The light comes on. You then need to check all 5 to see which one is low.*

GRPFAN

What a crock!

Take the dam things out and let me check my tires the old fashion way...........

MC5Wes

Thats the way TPMS works. A very simple system to maintain. When the light comes on. Its telling you the spare tire is low on air. Since it never gets checked.

Check all 5 tires the old fashion way. Make sure they are all the same PSI.

Press the reset button. And the light goes out.

If you remove the sensors. The light will be on all the time.

edbarrows

Thanks for all the replies. Finally managed to fix the problem with the assistance of the service manager at the dealership - turned out the problem was a device I had added to the car that was generating some EMF signals that were resetting the threshold pressures for the tires in a random pattern. The device was a system to record video in all four directions plus a doppler radar on the front to measure the distance to the car in front of mine and record the data on a hard disk in the back. It was part of a traffic safety study. Removed the add-on device and have had no further random TPMS lights. Interestingly, the Prius rerports the same interactions. Kudos and thanks to Rudy at Johnson Lexus in Durham for the help in sorting it all out.

Cruiter

Thanks for wrapping that up. Now it all makes sense. Nice post.