On-board safety systems are now everywhere in cars these days, from advanced safety features like pre-collision assist systems to more minor ones like tire pressure monitoring systems. In all cases, manufacturers install these features to help reduce the risks of crashing and getting injured on the road. For example, the NHTSA estimates that about 9% of all car crashes are tire-related.
It’s important to understand that keeping your tires correctly inflated and the tire pressure monitoring system on your vehicle in good working condition might one day save your life.
This article aims to explain what it means when the TPMS light comes up in your dashboard and what you need to do to turn it back off so you can be sure your tires are correctly inflated at all times while saving money on auto repair shop trips.
What Does TPMS Light Mean?
To correctly understand what you need to do when the tire pressure monitoring system warning light comes up in your dashboard, you first need to understand what makes it light up in the first place. The TPMS monitors the air inside the four tires at all times (sometimes 5, if your car is equipped with a tire pressure sensor on the spare tire). Whenever the pressure in one of your tires gets below a certain threshold, usually somewhere between 2 psi and five psi, the sensor will send a signal to the control module to let the driver know that something is not right. This is no matter if the air pressure drops slowly or all at once. The first thing that will happen then is that the low-pressure warning light will come up in the information display located on the dashboard.
The light might be of different color depending on the car brand you drive. Some vehicles will have different warning light colors to indicate the severity of the problem. In all cases, yellow means that you should watch out and go to the nearest repair shop as soon as you can, while red indicates that you need to stop the car right away or risk damaging your tires.
Symptoms of Low Tire Pressure
Low-Pressure Light Coming up
When a problem occurs, the TPMS warning light should light up steadily. If the light starts flashing instead, it’s usually related to a communication problem with one of the sensors or the TPMS control module. If it’s your case, read this article to learn the proper procedure to fix TPMS communication problems.
Low Tire Pressure Message in the Dashboard
Depending on your vehicle, a “low tire pressure” message may come up in the dashboard instead. Some cars use a low-pressure warning light, others use a text warning instead, and some even use both. Make sure you understand the different TPMS-related warning lights on your vehicle. If you need help with that, take a look inside your vehicle’s owner manual. The meaning of all dashboard lights should be explained in the Dashboard/Accessories section.
Unusual Noise Coming from one Wheel
Once a tire is significantly underinflated, the flat spot created on the lower part of the tire will start to make some “flop-flop-flop” sound as it rolls against the pavement. The sound may not be as audible at first, or if you drive at high speed, but you’ll definitely hear it at low speed. Once you start hearing it, you should stop the car as quickly and safely as possible, or you risk damaging the tire past the point of no return, and it will need replacing.
Jerky Steering Wheel
An underinflated front tire will make the steering wheel jerk from left to right. The lower the tire’s pressure, the softer the tire’s sides will be, and the steering wheel will be harder to keep straight. Once again, this will be more noticeable at low speed, but once the tire reaches a certain threshold, the steering will shake no matter the speed or road condition. If the low-pressure tire is located at the rear of the car, you might feel the rear starting to swerve. This is especially dangerous at high speed as you might end up losing control of the vehicle altogether.
Vehicle Pulling Towards the Side of the Road
If one of the front tires is underinflated enough, you might feel the car pulling to the right side of the road at low speed and when pressing the brake pedal to stop at a streetlight. You could also feel the same thing when driving on an uneven road.
Probable Causes of TPMS Light
Depending on the tire pressure monitoring system installed on your vehicle, you may or may not know which tire is causing the warning light to come up and if only one tire or more than one is low pressure. If you are lucky enough to own a car equipped with a smart TPMS, you might have an indicator in the dashboard showing the exact pressure inside each tire in real-time. If this is your case, you’ll know right away which tire is underinflated and where it’s located in the car.
If your car is only equipped with a yellow warning light, you’ll need to measure the pressure inside each tire to identify the problematic one. This step is crucial as the cause will differ whether the pressure is excessively low inside only one or more than one tire at a time.
In the case where only one tire is low-pressure, you can safely assume that the problem comes from a slow leak or, if the tire is completely flat, from a puncture somewhere in the tread. If, on the other hand, more than one tire is, for example, at 23 psi instead of 32 psi, it probably means that you haven’t checked the pressure inside your tires for a long time, and they have slowly deflated. This issue frequently happens with car owners installing their winter tires by themselves without re-adjusting the air pressure before leaving for a ride.
Even on perfectly sealed tires, the air pressure will drop an average of 2 psi per month. If you leave your winter tires mounted on rims in the garage for the duration of the summer, for example, it’s not unusual to find them 12 psi lower than what they were when they were stored. The same thing will happen with the tires currently installed on your vehicle. Even if you make sure the pressure is on point when you install your summer tires in May, the low-pressure warning light may come up in July, even if your tires are correctly sealed. The pressure in your tires should be checked and re-adjusted every month or so, no matter the season or the tire type.
How to Fix the Issue?
Inflate the Tire
The first thing to do when noticing that one or more than one tire is low-pressure is re-inflation. As mentioned before, if more than one tire needs re-inflating, you can safely assume that the cause is nothing but negligence, and re-inflating the tires back to the recommended pressure should be enough to fix everything up. This is except that, of course, you drove into a construction site, over a tipped-over nail box, and all your tires have been punctured. Such a situation doesn’t happen that frequently but, trust me, I’ve seen it before.
If only one tire is low-pressure, the condition of that tire will dictate the next steps. A flat tire usually means that the tire is punctured, and re-inflating it will be useless. You can always try it out if you want, as the hole may be small enough to allow you to reach the next auto repair shop without having to install the spare tire. If you decide to go this route, make sure to keep an eye on the tire as driving on a flat tire will damage it, and it will need replacing. If it deflates right back, you’ll have no choice but to install the spare tire or have your car towed and bring the punctured tire to a mechanic to have it patched up. If you are quite a handyman yourself, you might want to buy a flat tire repair kit, fix it yourself and save some money while you’re at it.
If the tire is only a little low in pressure, you might have a slow leak instead. Small cracks in the tire often cause slow leaks, or the air might leak around the rim. A nail might also have punctured the tire while efficiently plugging the hole simultaneously, only slightly allowing air to leak around the head of the nail. Slow leaks often take weeks to deflate. In that case, inflating the tire to the correct pressure should be enough for you to get to a repair shop without having to install the spare tire.
Reset the TPMS System
Once the tire has been fixed and you know that all your tires are inflated to the manufacturer’s recommended pressure, you’ll need to reset the tire pressure monitoring system. Once again, the appropriate procedure will depend on your car’s manufacturer and the type of tire pressure monitoring system installed on your vehicle.
If your car is equipped with a self-learning system, all you need to do is drive at a constant speed, over 60 km/h, for 5-10 min, and the system will reset itself. Dodge vehicles, for example, are often equipped with self-learning TPMS. Like older Toyota, some cars also had this same type of TPMS if only that the driver was required to press the “TPMS reset” button beforehand to enter the self-learning mode.
Cars equipped with manual learning systems will require the use of a TPMS tool to reset the system. You can either use the procedure specific to each car brand or the scanner to enter the learning mode and only then will you be able to reset and reprogram each TPMS sensor using a TPMS dongle. Ford vehicles are especially well-known in the auto mechanic world for their annoying TPMS manual learning procedure that needs performing every time you rotate the tires.
Recent vehicles are often equipped with a programmed learning system instead. These systems are by far the most complicated ones to reset. They will usually require an OEM OBD2 scan tool or a professional TPMS system programming tool to correctly reset the control module’s data. One could argue that this relearning procedure is car manufacturers’ latest attempt to prevent you from resetting the system at home. This is because programmed learning systems will often require a trip to the repair shop and a certified automotive technician’s help to be reset.
If you are unsure of which type of system equips your vehicle, take a look inside your owner’s manual in the TPMS section for more information about the appropriate TPMS reset procedure to perform after replacing or rotating your tires.
Is it Dangerous Driving with Low Tire Pressure Light?
The answer to that question depends on multiple factors like the speed you are driving at, the road’s condition, and how bad the tire is underinflated. While driving with a tire only slightly underinflated doesn’t pose an immediate threat, it can significantly increase the distance required to bring your car to a halt in case of an emergency braking situation. Driving with underinflated tires, just as much as overinflated tires, as a matter of fact, will also cause the tires to wear out unevenly, and it will also significantly reduce their average life expectancy.
Driving with a severely underinflated tire, on the other hand, can be a lot more dangerous. Driving at high speed, on the highway, for example, with one or more underinflated tires, may cause your vehicle to swerve or, even worse, the tire may explode suddenly, yielding a total loss of control and possibly a car crash.
Remember that the longer you drive on an underinflated tire, the more chances your mechanic won’t be able to fix it, and you’ll need to replace it altogether. When a vehicle drives on a low-pressure tire, the rim enters in contact with the tire’s side and will slowly cut it. Hitting a pothole with an underinflated tire may also damage the rim. While this is not too big of a problem if your car is equipped with black rims, it may be a lot more expensive to fix if you have installed shiny oversized chrome wheels.
To Sum It All Up
Having your tires inflated to the recommended pressure will not only reduce the chances of being part of a tire-related car crash but will also make you save thousands of dollars in the long run. Correctly inflated tires have a better footprint on the pavement, reducing inertia and resulting in a better fuel-efficiency. Tire pressure monitoring systems have proven their worth in numerous studies. They are, up-to-now, the best system found by car manufacturers to help remind people to keep their tires at the appropriate air pressure while ensuring they get their cut on maintenance-related work on yet another system. Luckily, once you’ve learned how TPMS works and what you can do to fix them when they don’t, you should be able to reduce the risk of having to stop by an auto repair shop for a low-pressure TPMS warning light problem in the future.