You are cruising down the street on a Sunday afternoon when suddenly the tire pressure warning light turns on. You haven’t felt any noticeable change in the car’s drive, but you still pull over and check your tires. Everything seems right, and a quick stop at the service station confirms that all tires are within operation specifications. What could be wrong?
Today, we will take a look at the two significant types of tire pressure monitoring systems. We will see how they operate and why they exist at all. We will also shed some light on the issues that plague such systems and the solutions you can use if faced with such a challenge.
- 1 What is a Tire Pressure Sensor?
- 2 How Does a Tire Pressure Sensor Work?
- 3 How to Reset the Tire Pressure Sensor?
- 4 What Does it Mean When the Tire Pressure Warning Light Comes On?
- 5 Conclusion
What is a Tire Pressure Sensor?
A tire pressure sensor is a device that, when triggered, results in the tire pressure warning light being displayed on the gauge cluster. It is the major component of the TPMS (Tire Pressure Management system). It warns the driver of under-inflated tires, with some systems capable of diagnosing individual tires in real-time.
Low-pressure in a tire causes higher fuel milage, faster wearing of tires, and in the worst case, cause the tire to burst.
How Does a Tire Pressure Sensor Work?
There are two major types of tire pressure management systems;
1. Direct TPMS
The tire pressure sensor is located on the wheel, attached to the valve, and works by sensing changes in the tire pressure. Its internal components measure the pressure, and the variation causes small changes in voltage. The voltage change is transmitted to a receiver in the car then sent to the car’s CPU, which works out if the tire has lost air pressure. If so, it displays a warning to the driver’s gauge cluster.
Such sensors are more common in the American market. They are known to corrode in harsh environments, and they cause a slight disturbance in the wheel balance due to the added weight. This can, however, be factored in and accounted for during wheel balancing.
2. Indirect TPMS
These systems work in tandem with the car’s ABS. The ABS works out the braking and the rotation speed of the wheels. The car’s CPU uses this data and information from the speed sensors to create parameters related to tire pressure. Tires with low pressure will rotate faster, and the TPMS will notice it. The difference in the rotational speed will indicate how much a tire has lost pressure. If the pressure loss calculated is below a given threshold, the tire pressure warning light will be triggered.
How to Reset the Tire Pressure Sensor?
There are several ways of resetting tire pressure sensors, and the methods depend on the type of TPMS you have. Regardless, the process should begin with you inflating all tires to the specifications and parking the car on level ground. Also, be sure to check if your battery is connected correctly and still has a full charge. Some systems draw power from them, and a flat battery may cause the transmitters and receivers to malfunction and trigger the warning.
For a Direct TPMS;
- Make sure the car is on, but the engine is not running.
- Consult with your user’s manual on where the reset button is located. Depending on your model, it may be on the dashboard, steering wheel, or in the glove compartment.
- Once located, press and hold the button until you hear a confirmation beep or horn from the car.
Resetting an Indirect TPMS;
- A simple DIY method uses a magnet. The magnet is placed over the transmitting valve of each tire in a specified sequence. A beep will be heard from the car immediately after each sensor has been reset.
- You can use a scanning tool from your mechanic or purchase one online. The scanning tool used will depend on your car’s TPMS, but it will typically give you some prompts to follow during the reset procedure.
What Does it Mean When the Tire Pressure Warning Light Comes On?
Loss in air-pressure in one of the tires is the primary cause of the warning light coming on. Ambient temperature change during the transition of winter and spring causes pressure variations in the tires. This also triggers the warning, but in most cases, it is a false alert that can be remedied by resetting the pressure sensors.
If the warning light is flashing on and off, it could mean that one of the tire’s pressure is very close to the minimum or maximum limits. When you start your car, and the warning light flashes for a while then stays on permanently, this could indicate a malfunction in the TPMS. Such would require you to visit a mechanic who might repair it or choose to replace a component within the system.
What Other Issues Cause the Sensors to Trigger the Tire Pressure Warning Light?
- Rotating Tires
Tire rotation involves swapping the tires diagonally across the car. This is done to ensure the tires wear out evenly. Rotating the tires might trigger the warning if the TMPS misdiagnoses the rotation as an air-pressure change in a given wheel.
- Changing Tire Pressure
Off-road drivers usually reduce the air pressure in their wheels when they get stuck in a bog. Low tire pressure increases the tire’s surface area, increasing traction. Reducing the air pressure, most probably than not, triggers the warning.
- Changing the Tire Size
Vehicles with the TPMS linked to the ABS tend to trigger the warning when the tires are replaced with larger or smaller diameter tires. The unique way that the ABS measures tire-pressure is affected since smaller tires turn faster than larger diameter tires. The difference in rotation speed can trigger the warning.
Note: Guys with vintage and older car models can also upgrade to use TPMS. There are loads of aftermarket options that you can install and get that extra layer of safety.
The tire pressure warning light exists for a reason: to warn the driver. Sudden changes in tire pressure indicate a tire burst waiting to happen. To have a tire burst while driving fast will most likely end in an accident.
Even though ambient temperate changes may affect the tire pressure, we now know it’s only to a small percentage. We should never ignore this warning, and it’s advised to immediately pull off the road and inspect our tires as soon as it comes on. If the tire pressure sensors are the cause of the issue, you now know how to reset it yourself and when to have a trained technician sort it out for you. Remember to always keep the cap on your tire valve stem tightly sealed.
Does your car have a tire pressure monitoring system? Has the tire pressure warning light ever turned on while you were driving? What other solution to tire pressure sensor issues do you know of?
Read more: SRS Light: Why Is It On? What To Do?