A number of car models now come with a built-in tire pressure monitoring system (TPMS). Whenever the air pressure in your tires drops below the ideal temperature, a light would come on in your dashboard indicating so. Through the dashboard information system, you should be able to locate a menu where it would indicate which of the 4 tires are having the issue.
But just because the TPMS light is on, it doesn’t always mean that something needs replacing or your tires need maintenance. When this occurs and all your tires appear normal, many drivers are left to wonder why is my tire pressure light on when my tires are fine.
This is due in part to the light could also come on due to a number of reasons, such as outside temperature. This is why it is recommended to always have a tire pressure gauge on-hand in the car to double-check and verify.
What is Tire Pressure Monitoring System (TPMS)?
Let’s talk more in detail about what exactly is TPMS or Tire Pressure Monitoring System. It is a small chip that is stored inside each of the tires on your vehicle.
The only job it has is to monitor whether each of the tires is inflated to the proper air pressure. Some call this the tire pressure sensors, others may just refer to it as TPMS.
When the chip reads the temperature to be 25% below the recommended number, the TPMS light on your dashboard will be triggered on your dashboard. At which point, you should first check and verify that your tires are indeed low on air pressure.
How does Tire Pressure Monitor Sensor Work?
Every tire pressure monitor system has sensors that monitor each wheel independently and a digital receiver somewhere in the car. An indicator light will come on on the dashboard when the tire pressure is too low. Some car models will also let you know each of the tires’ conditions individually.
Generally speaking, there are two types of sensors:
With Direct TPMS, sensors are installed on all four wheels. A signal is sent to the digital receiver when the tire pressure is low. This system is more common in most cars.
Due to the location of where the sensors are installed, there could be a risk of wear-and-tear or damage from tire service or when going over harsh bumps. Some variation of this system may have the sensors installed to the tire valves, which is where the entry point for air on each tire.
Instead of monitoring with a sensor on the wheels, this kind of monitor from the Anti-Lock Brakes instead. Sensors are in place to monitor rotation speed and the system will determine that the tire pressure is too low when the rotation speed is too slow. This type of system tends to be more durable and is less likely to damage or have issues.
How to Know if the TPMS Warning is On?
When a tire’s pressure is low, you will notice the TPMS light in the dashboard lighting up usually in yellow. If you see this, you should double-check the tire pressure on all wheels with a physical tire pressure monitor.
You can do this with a tire pressure meter (you can get one cheap from most stores). If you don’t have one, you can go to a local gas station or tire shop, they should be able to help you check.
Check the recommended pressure in the vehicle’s instruction manual, you may find this information hidden on a label in the inner door panel on the driver side
Fill up to the correct air pressure amount. After, the TPMS light may need a few minutes to reset and should go off after driving for a little while.
If you notice that the light continues to stay on for long periods, this could be because of something simple (a reset is needed) or you may have to bring it into the shop (replacement may be needed on one or more sensors).
Keep in mind that if you see the TPMS light coming on for a couple of seconds each time you start your vehicle, this does not mean the tire pressure is low. In fact, all the lights on the dashboard always come on for a couple of seconds when the engine first starts, it is a way to ensure that the light is functioning.
If you see the light never coming on even when you first start the car, you should contact your local dealership and have it checked immediately. In either case, it is always better to figure it out sooner rather than later.
What Does It Mean When the TPMS Light is On?
You may notice the TPMS light behaving in a number of ways:
TPMS Light stays on all the time
This could either mean air pressure in one or more of your tires is low. If you have already checked and know that this isn’t the case, then it could indicate that the TPMS sensor is not reading correctly.
TPMS Light Blinks for a Minute then Stays On
You may notice that the TPMS warning light blinks for about a minute or so when you first start the vehicle, then proceed to stay on constantly. If this is what you are seeing, you should make an appointment with your local dealership and have it checked immediately.
TPMS Light Coming On and Off Periodically
If you see the TPMS warning light sometimes on and sometimes off, this could be an indication that the tire pressure reading is affected by outside temperature.
This is typically due to cold weather during nighttime or winters affecting the tire pressure reading. When the temperature goes back up, the reading will go back to normal. This is a very normal occurrence and is no cause for alarm. Either way, it wouldn’t hurt to double-check the air pressure whenever you are coming out of winter.
Why Is It Important to Maintain Proper Tire Pressure?
For optimal driving and gas mileage, you should always ensure that the tire pressure is set correctly.
When tire pressure is low, the tire will have more contact with the road surface which could lead to damage to the tire. Unless you are driving on snow, gravel or sand, it is not recommended to have underinflated tires when driving.
Air pressure too high may lead to a stiff ride and increase wear on the tire. Too much friction and heat will cause the tire to wear down prematurely which could lead to a tire blowout or the tire tread to be worn down quicker.
Keep in mind that the Tire Pressure Monitor System is designed to monitor only low air pressure. You may not realize that you are driving with high pressure which is why it is always recommended to use a separate tire pressure meter and check regularly.
To recap, you definitely want proper tire pressure because it will:
Slow tire tread wearing
Your tires will have a longer lifespan and will save you from having to buy tires less often.
Reduced rolling resistance
Your car will drive a little longer per tank with a lower loss of energy to rolling resistance.
Better resistance to moisture
Your car will be more equipped to stay in control when going over water, reducing the risk of your tires losing grip on the road surface.
Why is the Tire Pressure Light On When the Tires Are Fine
The next time you ask yourself ‘why is my tire pressure light on when my tires are fine’, considering that there are a number of reasons why this is happening:
Outside Temperature Change (Most Likely)
If you are living somewhere where mornings tend to be cold, you should avoid filling and measuring tire temperature in the morning. This would likely lead to too much air going into the tire for driving through the day when the temperature is warmer.
This is also why when the outside temperature drops. Because the density of air is different when the temperature is warm vs cold, the tire pressure warning may come on since the reading is affected by the cooler temperature.
Tire Change or Rotation was Recently Performed
The tire sensors may be in need of a reset if the tire position on the wheel was changed. Depending on the car, this may just mean that you need to drive around for a few minutes so the tire can reset. If this doesn’t work, you may need to request a full calibration at the dealership or tire shop.
And not all tires have tire pressure sensors, so if you are buying tires, new or used, you should make sure that the tires have TPMS sensors if you want the car to be able to provide a warning when you are using it.
The TPMS Sensors are damaged
Because of where the sensors are located on TPMS Direct system, they may become damaged over time when going over hard bumps or when the vehicle goes through tire service. The onboard battery may also be an issue over time as they are expected to last around 5-10 years.
If the physical tire experiences damage or if it is injected with something different from air or nitrogen (such as flat-repair sealants or fix-a-flat), the sensor could also be damaged in this case as well.
The wheel speed sensors are faulty
On TPMS Indirect system, the wheel speed sensors could become damage and may give off the wrong signal.
Pressure in Spare Tire is Low
It’s not often the spare tire would have a TPMS sensor, but it’s also not impossible. If you are using a spare tire and your TPMS warning light comes on, this could be the reason and it is not a problem since you are most likely only using the spare tire on a temporary basis.
What to do when your low tire pressure light won’t turn off
If this happens, you should find a safe place and have a look to see if any of your tires are starting to look flat, Some cases it could be just a need to fill more air into the tire and have the air pressure back up to the correct level.
Be sure to check all the tires and their pressure level as sometimes there could be more than 1 tire in need of attention. If the tire looks flat, change it out and use your spare tire and have the tire replaced soon.
What to do if the TPMS Warning Light Comes On When Driving in Colder Weather
You may notice the TMPS light coming on in the morning or whenever the temperature drops to a colder temperature. The TPMS warning light may come on when the air pressure drops to 25% on one or more of the tires.
Before you go and inflate the tires up thinking that the air pressure is too low, do be careful because doing so may lead to the air pressure being too high during the warmer part of the day.
The best practice is to go by the air pressure reading during a part of the day when it is warm. If the reading is correct and the TPMS warning light only comes on during the colder portion of the day, then you will know that the sensor’s reading is just affected by the temperature and can ignore the warning light.
I’ve Added Air but the TPMS Warning Light is Still On
Normally, TPMS Light will turn off when all tires are inflated to the proper amount. This can sometimes take several minutes before the TPMS Light turns off. But if this doesn’t happen,
The first thing to do is to use a tire pressure meter and get a second reading to see if the air pressure in the tire is correct.
If it is and the light continues to stay one, this could be an indication that one or more of the tires are leaking air. If you have checked and this is not the case, then it may just be that the pressure sensors are faulty and repair will be needed.
If you see the TPMS warning light comes on for 1 second, then off for 3 seconds repeatedly, this is likely an indication that the vehicle is picked up issues with the sensor, you should contact your dealership as soon as possible and have the vehicle serviced.
Is It Safe To Drive The Car When the TPMS Warning Light Is On?
If you ignore the TPMS Warning, over time this could become major tire issues that could potentially cause problems for you as well as other drivers on the road.
If your wheels are underinflated, it could lead to tire failure, blowout, and possibly tires being overheated, something that you should consider seriously. You will notice poorer control over the drive with the car becoming less willing to drive straight.
On the reverse, if tires are overinflated, the tires will wear faster and driving will be noticeably bumpier with less road impact absorbed.
You may find that the vehicle can be driven with no or very little issue when the TPMS warning light is on, but over time, it will lead to:
- Increase wear on the tires
- Poor driving response
- Tires overheating
- Reduced tractions
- Bumpier ride with less traction
How To Fix the TPMS Sensor?
In many cases, the fix may just be to check and ensure that air pressure in each tire is adequate and at the level that is stated either in the instruction manual or shown on the inner driver door panel.
If the case is that your TPMS light is faulty, then you should contact your dealership to arrange to have it checked and fixed as soon as possible.
Generally speaking, fixing the TPMS light is an easy task, so even if your warranty is over, the cost of fixing should be relatively low, likely around $100-300. Check to see if your warranty is still valid, it may allow you to have this done at no cost. Or you may find a capable local tire shop to get this done for lower cost too!
How To Reset the TPMS Warning Light
Most cars generally provide a DIY method to reset the TPMS light. Check the owner”s manual to check and see if there’s a specific way to reset the TPMS warning light.
On some models, there is either a button to reset in the glove compartment or inside the car settings menu. Once you locate the setting, try putting your car on idle (start the car but not the engine) first, then hold the reset button and wait around 3 seconds. You should hear a beep when the TPMS warning light goes off.
Next, turn the engine on and drive the car around for around 30-45 minutes while keeping a steady speed of at least 30km. Once this is done, the TPMS sensor should be successfully reset.
On Toyota vehicles, the steps are similar, you simply start the car, press and hold the TPMS button while the TPMS light flashes 3 times slowly. Afterward, release the button.
There are some brands of cars that don’t provide a DIY method to reset the TPMS sensor, so this method may not work for you.
You shouldn’t have to reset the TPMS sensors frequently or regularly. If the TPMS sensor comes back on and stays on, consult your dealership to have a check on the TPMS sensors as they may be faulty.
Is it a Good Idea to Replace the TPMS Sensors?
If you have already tried all the ideas on this page and still find that the TPMS sensors are not working properly, This may mean that replacement is the only remaining option. Your local dealership is likely to provide tools and diagnostic to confirm whether if the sensors are in need of replacement.
Is the TPMS Sensor Accurate?
The Tire Pressure Monitoring System is designed to give you a quick view of each tire’s air pressure level but it can be misled by outside temperature or damaged.
The best practice is to also do a visual check of your tires every day or so. It doesn’t have to be thorough but at least you would know that something is wrong.
Another good practice is to keep a tire pressure gauge or meter in the car, this can be purchased from most car accessories stores. This tool is very handy to use. When your TPMS warning light comes on, it can be used to verify and validate the reading that the car’s TPMS is giving you, ensuring that it is accurate.
What Can I Do To Reduce TPMS Warnings?
There are steps you can take to reduce the chance of the TPMS Warning coming on by performing some easy regular maintenance on your car. You can check the tire pressure every week or whenever you wash your car.
If you tend to drive the car frequently or often for long trips, be sure to have the TPMS sensors checked every 4-6 months. You also should change and replace the wheels before it is worn out.
You should always have your wheel changed or handled by a trained professional or have your dealership’s service department handle it for you.
In conclusion, if you see the TPMS light comes on, it is likely an indication that air pressure is low on one or more of your tires. However, you should not solely rely on the reading from the car’s TPMS, there are a number of factors that could affect the TPMS sensors to go off even though your tires are actually fine.