how do you test low air pressure warning signal

How do you test low air pressure warning signals? Many people ignore the air pressure warning signal, but you should not make this mistake.

Those warning signals tell you a lot about the condition of your vehicles or any machinery.

You need to consider them to make the necessary changes.

But, again, how can you test low-pressure warning signals in the first place?

It involves starting the engine and then leaving it in the “on” position to let the pressure system take effect and notice what indicators say.  

The Perils of Ignoring Low Air Pressure Warning Signal

All drivers know that low pressure in a car tire can create problems.

The car becomes heavy, awkward to handle and there is three times the danger of a collision.

driving while tire is low pressure

Even without a crash, there is still the possibility of damaging the car if you try to drive.

Damage to the wheel and the wheel rim can be very expensive to replace.

And there could be damage to the brakes and the steering, which cost considerably more to put right.

Ignore the low-pressure warning at your peril or prepare for safe, worry-free driving by learning how to test the low-air pressure warning signal.

Fact: Never leave a car parked in one spot for too long, as doing so can cause the rubber on the tires to flatten and lead to a dangerous ride. 

What is Low Air Pressure Warning? 

The low air pressure warning is a light that flashes when the vehicle’s tire pressure monitoring system (TPMS) detects low pressure in a tire.

It is set with the other gauges on the dashboard.

warning light of tire air pressure

Sometimes the light takes the form of an icon representing the cross-section of a tire, with an exclamation point in it.

The TPMS keeps track of all the tires but will be activated even if it is only one that has lower pressure.

These systems are designed to help motorists keep their tires at optimal performance.

It is also essential for driver and passenger safety and for fuel efficiency and general wear and tear on the wheels and engine.  

An Important Thing to Remember

tire pressure check

Tire pressure is measured in pounds per inch (psi).

And most modern systems are capable of detecting even smalls decreases in pressure.

It could be an indication one of the tires has a slow leak perhaps from a puncture or faulty valve.

Fact: Tire pressure should be checked regularly and the recommended amount can usually be found in the owner's manual or the driver's side door sill. 

How Do You Test Low Air Pressure Warning Signal? 

Tire pressure is best checked when the tires have been driven for less than a mile and are still cold.

From there it is just a few simple steps that should take less than 10 minutes to perform:

  • Locate the air pressure supply available on almost all gas station forecourts.
  • Look for and make a note of the recommended psi for your car’s make and model.
  • Find the PSI ratings either on a panel on the driver’s door or in the user manual.
  • Remove the valve caps from each tire and keep them safe.
  • Start the compressor.
  • Place the pressure gauge directly on each of the valve stems in turn and press down until the hissing sound made by escaping air stops and the reading is given.
type of compressor

Depending on the type of compressor the air supply will cut off automatically with a signal, usually a bleep, when the tire has reached pressure.

Alternatively, you may have to release the gauge manually when the pressure is reached. 

How the Air Pressure Sensor Works

The air pressure sensor is programmed to detect changes in pressure within the tire.

Some may be within acceptable limits but the system is programmed to throw a warning light when the detected levels are too low at a drop in pressure of about 25%.

how the air pressure sensor works

The sensor is situated within a small, pressurized pocket made by the tire and wheel and uses low frequency radio waves to transmit its data to the onboard computer.

Fact: Gas mileage drops by 2% for every 5 psi if a tire is underinflated. 

Why Should You Test the Low-Pressure Warning Signal?

Testing the low-pressure warning signal is simple and a test that can quickly be adopted as part of your own car home maintenance routine.

checking tires

Checking your tires to keep them at the correct pressure is the easiest way to enjoy many benefits. It can help to:

  • Prolong tire life
  • Secure better fuel efficiency
  • Enjoy a smoother drive with a better steering response 

The Importance of Checking Low-Pressure Warning Signals

With computerization and sensors, modern monitoring systems seldom make mistakes.

But, still, a warning light on a car should never be seen as just a suggestion to check something over when you have time.

Still, the recommendation is to check the low-pressure warning signal about once a month.

This is because the sensor itself is powered by batteries that although are long-lived can expire.

Knowing your TMS is working efficiently provides peace of mind but also confirms that if it comes on you need to take the warning seriously. 

Checking Low Pressure in the Braking System

checking the brake system

Vehicles and machinery that use compressed air, such as cars and trucks, should have their low air pressure warning signals checked regularly to ensure their continued safe operation.

When it comes to checking the low pressure, you should never ignore the braking system.

The ability to stop the car and the likelihood of accidents are both negatively impacted by low air pressure in the brake system.

Other concerns, such as diminished engine performance and trouble shifting gears, might be brought on by low air pressure as well. 

Three Types of Low Air Pressure Warning Devices

Since 2008 all new cars have had a system fitted that monitors the air pressure in the tires.

It is a safety feature; underinflated tires are unstable and more susceptible to blowouts.

The three types of low air pressure warning devices are valve stem direct TPMS, banded type TMPS and indirect TMPS. 

Valve Stem Direct TMPS

valve stem direct tpms

The device relays information about air pressure, temperature, location and the charge in the battery to the electronic control module, ECM.

Direct TPMS

It has a sensor on each wheel to monitor the tire’s air pressure.

The system transmits the data to the car’s computer system and triggers the warning light when the pressure is low.

A vehicle is more likely to have direct TPMS if the stems are held in place with nuts at their base, the tires may have pressure sensors inside. 

Indirect TPMS

Indirect tpms

It is a system that makes use of the rotation speed of each tire and the car’s antilock braking system.

When a tire’s pressure is low it rotates at a different speed than the other tires.

It is this information that is detected by the system and triggers the warning light.

Tips to Avoid Low Pressure

All tires slowly lose pressure.

The loss occurs naturally via osmosis and is one reason why a monthly tire pressure check is essential.

tips to avoid low pressure

Similarly, chemicals and debris on the road, corrosion and poor driving conditions also affect the wheels, tires and tire pressure.

Tire pressure also drops in colder weather, around 1psi per 100F, which is something to be aware of.

Avoiding low pressure essentially means keeping a check on your tires and wheels using a calibrated gauge to check them.

Other things to keep an eye include:

  • The valve which can sometimes need replacing before the tire itself.
  • Corrosion anywhere around the wheel well can prevent a tight seal.
  • Embedded objects, such as screws and nails, in the tire itself.
  • Bead damage, is when the seal between the tire and the metal of the wheel becomes corroded or damaged causing a leak.
  • The tire and wheel’s round shape can be compromised by negotiating potholes and raised sidewalk curbs.
Fact: Tires with low air pressure wear out faster and more unevenly than those with normal pressure as more of the tire's surface is in contact with the road. 


How do you test low air pressure warning signals? Simply start the engine, let it idle for a few minutes before turning the engine off.

Check the warning lights and then wait for the pressure system to take effect.

Paying attention to the low air pressure warning signal and taking fast action to fix the problem is crucial.

Tire pressure, air brake leakage, and other maintenance tasks may fall under this category.

Following these procedures will ensure the security and dependability of your vehicle or machinery.