I need advise please. My flat tire sensor light came on recently after changing to new tires and AR1 17" rims. The tires came via UPS already mounted on new wheels, So I put them on myself, and took for a test drive. No problem, except the tires were unbalanced. I took them in for balancing, and now the yellow light stays on constantly. I've altered tire pressure, and taken the car back to shop a couple of times, but no luck. Any advise out there?

 

Have you tried resetting the system? Turn the key to the first stop, press and hold the reset button next to the parking brake until the light comes on, and then start and drive the car normally. The light should go out after a few seconds.

The light is really a low pressure or pressure difference sensor. It measures wheel speed and compares it to the other wheels. If one tire gets low on pressure, it will rotate at a different speed. When that happens, the light goes on.

If all tires are equally low, nothing happens as the wheels are all rotating at the same speed. (so I've been told)

Whenever you change tires/wheels the system will probably need to be reset.

 

Did you reset your monitor? On my car, it's a button directly below the hand brake.

Edit- Morris, you beat me to it!

 

YES, Thanks guys, I tried that, but I'll do it again in case I screwed it up some how.

 

What good is a sensor that doesn't actually measure pressure.

Also, has anyone had issues with run flats losing air over time? Like going from 35psi to 22psi in about 6 months. But, since of all the tires are losing at the same rate the sensor doesn't go off, you have no idea untill you check it. I know, I know, you should check it everytime you get gas, but who has time for that?>?

 

Actually, checking when you buy gas is probably not the best way to check tire pressure. It should be checked when the tires are cold, such as after sitting over night. If you have the car in a garage, that's best as you can check it every week or two before you drive it. If you park outside, you might need to watch when you check it. I've checked tires outside when the sun was shining on one side of the car and that side was higher. Depends on how picky you want to be.

I believe there are two types of tire pressure monitoring systems available. One uses the ABS sensors (I believe) to monitor rotational differences. That's what the Mini has. There are other systems that employ pressure transducers located in the wheels that will actually give you a direct pressure readout. I have a Jeep Liberty that has a pressure read out that allows you to check the actual pressure. It went off shortly after I bought it and the spare was showing low. I guess the dealer didn't check the pressure before delivery.

More and more cars and trucks will probably have some type of tire pressure monitoring system as more cars go to run flats. I think I've read about legislations requiring tire pressure monitoring systems too.