TPMS Light: Why It Stays On
A solid TPMS light means low pressure; a flashing one means a system fault. Why the light stays on after you add air, and how to fix sensors and relearns.
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The tire pressure monitoring system (TPMS) light is the yellow horseshoe shape with an exclamation point. Federal safety rules have required TPMS on new passenger cars and light trucks since the 2008 model year, and the system is designed to warn you when one or more tires is significantly underinflated. When the light stays on after you have added air, the cause is almost always one of a handful of things.
The first step is to notice how the light behaves when you start the car, because a solid light and a flashing light mean different things.
Solid vs flashing: what the light is telling you
| What you see | What it means | What to do |
|---|---|---|
| Light comes on and stays solid | One or more tires is low, often 25% or more below the recommended pressure | Check all tires with a gauge and inflate to the door placard |
| Light flashes for about a minute at startup, then stays solid | A system malfunction: a sensor, receiver or module problem | Tires may be fine, but check them manually; get the system scanned |
| Light comes on in the morning and goes off after driving | Pressure is borderline and rises as tires warm | Add air to the placard pressure when tires are cold |
| Light came on after a tire service | Sensor damaged, not relearned, or a non-sensor wheel installed | Return to the shop for a relearn or check |
- Light comes on and stays solid
- What it means
- One or more tires is low, often 25% or more below the recommended pressure
- What to do
- Check all tires with a gauge and inflate to the door placard
- Light flashes for about a minute at startup, then stays solid
- What it means
- A system malfunction: a sensor, receiver or module problem
- What to do
- Tires may be fine, but check them manually; get the system scanned
- Light comes on in the morning and goes off after driving
- What it means
- Pressure is borderline and rises as tires warm
- What to do
- Add air to the placard pressure when tires are cold
- Light came on after a tire service
- What it means
- Sensor damaged, not relearned, or a non-sensor wheel installed
- What to do
- Return to the shop for a relearn or check
The 25% figure comes from the federal TPMS standard, which sets the warning threshold relative to the vehicle's recommended cold pressure. Many systems warn earlier. Your owner's manual describes your car's specific behavior.
Why the light stays on after you add air
You inflated to the wrong number
The correct pressure is on the placard in the driver's door jamb (sometimes the fuel door or glovebox), not the number molded into the tire sidewall. The sidewall number is the tire's maximum pressure. Inflating to the placard and checking all four tires, plus the spare on vehicles that monitor it, solves a lot of "stuck" lights.
You measured warm tires
Placard pressures are cold pressures, meaning the car has been parked for a few hours or driven less than a mile or so. After driving, tires read several psi higher. If you set them to the placard while hot, they will be low again the next cold morning.
It got cold
Tire pressure drops roughly 1 psi for every 10°F drop in air temperature. A tire set correctly on a warm afternoon can trigger the light on a cold morning. This is why the light often appears with the first cold snap of fall. Our winter car prep checklist covers what else to check then.
The system needs to relearn or reset
Many systems clear the light on their own after you drive for several minutes above a set speed. Others need a reset:
- A reset button, often under the steering column or in the glovebox, on some vehicles.
- A menu setting in the instrument cluster or infotainment screen.
- A relearn procedure after rotating tires or replacing sensors, which on some vehicles requires a TPMS tool that wakes each sensor in order.
The exact method depends on your make, model and year. Check your owner's manual, or decode your VIN first so you are reading the right procedure for your exact model.
The spare tire is low
Some vehicles have a sensor in the full-size spare. A spare that has been sitting low for years can keep the light on even when the four road tires are perfect.
A slow leak
A nail, a leaking valve stem, a corroded bead seal on an alloy wheel, or a bent rim can lose a few psi a week. If one tire keeps going low, have it inspected. Spray soapy water on the tread, valve and bead and watch for bubbles.
Direct vs indirect TPMS
Cars use one of two system types, and the fixes are different.
| Direct TPMS | Indirect TPMS | |
|---|---|---|
| How it works | A battery-powered sensor in each wheel reports actual pressure by radio | Uses ABS wheel speed sensors; a low tire is smaller and spins faster |
| Shows individual pressures | Usually yes | Usually no |
| Common faults | Dead sensor batteries, damaged sensors, missing relearn | Needs recalibration after inflating or rotating |
| Reset | Often automatic or with a tool | Usually a button or menu, then a drive |
- How it works
- Direct TPMS
- A battery-powered sensor in each wheel reports actual pressure by radio
- Indirect TPMS
- Uses ABS wheel speed sensors; a low tire is smaller and spins faster
- Shows individual pressures
- Direct TPMS
- Usually yes
- Indirect TPMS
- Usually no
- Common faults
- Direct TPMS
- Dead sensor batteries, damaged sensors, missing relearn
- Indirect TPMS
- Needs recalibration after inflating or rotating
- Reset
- Direct TPMS
- Often automatic or with a tool
- Indirect TPMS
- Usually a button or menu, then a drive
If your dashboard shows each tire's pressure, you almost certainly have a direct system.
Sensor problems (direct systems)
Dead sensor batteries
Direct TPMS sensors have sealed batteries that cannot be replaced separately. They commonly last somewhere around 5 to 10 years, depending on the design and how much the car is driven. When one dies, you get the flashing malfunction light. On older vehicles, sensors often fail one after another, so some owners replace the set at the next tire change to avoid paying for mounting labor several times.
Damaged sensors
Sensors can be damaged during tire mounting, by corrosion at the valve stem (common on sensors with aluminum stems in road-salt regions), or by impacts. Tire sealant from a repair kit can also clog the sensor port on some designs.
Wheels without sensors
Winter wheels or aftermarket wheels without sensors will trigger the malfunction light. You can add sensors to the second set of wheels, or accept the light for the season and check pressures manually.
Typical costs
| Repair | Typical cost (estimate) |
|---|---|
| Sensor relearn or reset at a shop | about $0 to $50, often included with tire service |
| Replace one sensor, installed | about $50 to $250 |
| Valve stem service kit | about $5 to $15 per wheel in parts |
| Set of four sensors with a new tire set | about $150 to $500 |
- Sensor relearn or reset at a shop
- Typical cost (estimate)
- about $0 to $50, often included with tire service
- Replace one sensor, installed
- Typical cost (estimate)
- about $50 to $250
- Valve stem service kit
- Typical cost (estimate)
- about $5 to $15 per wheel in parts
- Set of four sensors with a new tire set
- Typical cost (estimate)
- about $150 to $500
Costs are typical estimates and vary by vehicle and region. OEM sensors usually cost more than aftermarket ones that are programmed to match.
A five-minute check you can do now
- Let the car sit for at least three hours, or check first thing in the morning.
- Find the placard pressure on the driver's door jamb. Front and rear can differ.
- Check every tire with a reliable gauge, including the spare if it is monitored.
- Inflate to the placard. Do not use the sidewall maximum.
- Drive for 10 to 20 minutes at normal speeds. Many systems clear on their own.
- If the light stays on, try the reset or relearn procedure in your owner's manual.
- If the light flashes at startup, the system has a fault. Have it scanned by a tire shop or with a scan tool that supports TPMS.
Our guide to checking tire pressure and tread depth covers gauges and tread measurement in more detail.
Why the light matters
Underinflated tires flex more, build heat, wear faster on the edges, hurt fuel economy, and can fail. NHTSA's tire safety information (opens in a new tab) explains how pressure, load and tread depth affect safety, and lets you check tire recalls. TPMS is a backstop, not a substitute for a monthly gauge check, because a tire can be meaningfully low before the light triggers.
If you track tire rotations, pressure checks and sensor replacements in your free CarManager garage, you can see at a glance when sensors are reaching the age where they start to fail.
Frequently asked questions
Why is my tire pressure light on when my tires are fine?
The most common reasons are inflating to the wrong pressure (the sidewall instead of the door placard), checking while tires are hot, a cold morning, a low spare, or a system that needs a reset or relearn. If the light flashes at startup before staying on, the system itself has a fault.
Can I drive with the TPMS light on?
If you have checked the tires with a gauge and they are at the correct pressure, you can drive carefully while you sort out the system. If you have not checked them, assume a tire may be low. Driving on a significantly underinflated tire can damage it and affect handling.
How do I reset the TPMS light?
It depends on the vehicle. Many systems reset after driving for several minutes once the tires are correctly inflated. Others use a button, a dashboard menu, or a relearn procedure with a TPMS tool. Your owner's manual has the exact steps.
How long do TPMS sensors last?
Direct TPMS sensor batteries commonly last somewhere around 5 to 10 years, depending on design and use. The battery is sealed in the sensor, so the whole sensor is replaced when it dies.
Does rotating my tires affect the TPMS?
On some vehicles, yes. Systems that show each tire's position may need a relearn after a rotation, or they will show pressures on the wrong corners. Indirect systems often need recalibration after rotation or inflation.
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General guidance, not professional advice. Intervals, specifications and legal requirements vary by vehicle, manufacturer and state: your owner’s manual, a qualified mechanic and your state agency come first. Costs mentioned are estimates. Our data sources.