Why is my TPMS LIGHT on?
If your low tire pressure light is on, the most common reason is that your tire pressure is low. If this is the case, the fix is simple! Inflate the tires to the proper pressure and the TPMS light should go out after you’ve driven the car for a few minutes.
Since you likely found this page because you were searching Google, you’ve probably already tried filling the tires, yet the TPMS light is still on. Why?!
The Low tire pressure light is on, but the tires are fine!
There are a few reasons why your TPMS may still be on after filling the tires.
- The car may need to be driven to turn off the TPMS light
- The TPMS must be reset
- There is a fault with the system
- Your spare tire may have a tire pressure sensor too
If the tPMS LIGHT won’t turn off, drive the car first.
There are two types of TPMS. Direct and indirect.
- Direct systems have an electronic pressure sensor in the wheel that broadcasts data to the control unit.
- Indirect systems use the ABS wheel speed sensors to count the revolutions of each wheel. When driving straight, if each wheel has the same tire pressure, they will all rotate equally. If one tire is low, it will rotate more times than the others.
Direct systems sometimes require movement for the sensor to start broadcasting or the control unit to start receiving. If you fill the tires and the pressure is OK, but the tire pressure light won’t go out, drive the car before doing anything else.
Indirect systems have no way to know what the tire pressure is unless the car is moving. If you fill the tires, the control unit won’t know that the tire pressure is OK until you drive the car in a straight line for a while.
Reset the tire pressure light
On most cars there’s no need to reset the tire pressure light. Fill the tires and the light goes out. But since you’re still reading, maybe this hasn’t worked for you. Some Toyota systems allow the driver to set the tire pressure limit by resetting the normal pressure values in the control unit. If the TPMS light is flashing right after you start the car, you SHOULD NOT reset the TPMS. I’ll explain later. However, if the TPMS light is on solid all the time, resetting the TPMS may help.
Toyota TPMS reset
Turn the car to “ON” or “Ready/Running”. If one power mode doesn’t work, try the other. Press and hold the TPMS reset button. Its location varies car to car, but you’ll usually find it on either the driver’s lower dash or in the glovebox. You’ll be able to identify it by the TPMS symbol on the button. It looks just light the TPMS light on the dash – often described as an upside-down horseshoe with an explanation point in the middle. Watch the TPMS light on the dash. Wait for it to blink three times, then turn the car off. You may need to drive the car before the TPMS light turns off.
Honda TPMS reset
Some Honda vehicles use an indirect TPMS system that requires calibration any time tire pressures are changed, tires are replace, or wheels are rotated. Honda TPMS light resets either work like Toyota, with a button marked with a symbol that looks like the tire pressure warning light, or can be reset through the information display and steering wheel buttons. Once again, you’ll likely need to drive the car before the light will go out.
Mazda TPMS reset
Many Mazda vehicles use an indirect TPMS system. Performing a reset is usually the same procedure as Toyota, but for some reason on many Mazda vehicles, the TPMS light won’t go out after the tire pressures corrected and the light reset. The solution that works for us is to reset the system twice.
Subaru TPMS reset
Subaru seldom has the newest technology with a few exceptions. Luckily, the direct TPMS system they use is simple and reliable and driver’s are seldom plagued with tire pressure warning lights that won’t go off. Currently, no Subaru models require resets.
Blinking tire pressure light
Why is your tire pressure light blinking? A blinking TPMS light is caused by a system fault, not low tire pressure. When people call for advice about a TPMS light that won’t go out after setting the tire pressure, I’ll ask if the light is blinking. Often, they’ll say no, but later I’ll find out that it was. Some cars only flash the TPMS light for a short time after startup. Then the light will go solid.
If you have a Toyota, don’t try to reset TPMS if the warning light blinks after startup. It will cause the system to get “stuck”. If this does happen to you, fix the fault with the TPMS system first, connect a battery charger to the car, jumper pins 13 and 4 on the OBDII connector, and then leave the car sitting with the key on for at least 30 minutes. This will get it “unstuck”.
On some Honda cars there is a separate tire pressure fault light instead of a blinking light. It’s the letters “TPMS”.
Other articles you may like
Tire pressure monitoring systems (an old article)
Should TPMS sensors be resealed?
A Consumer Reports article on tire pressure and ambient temperature