Why Is My Tyre Pressure Monitor Light On? Causes, Fixes, Prevention

Introduction
Seeing your tyre pressure monitor light suddenly illuminate can feel alarming—especially if you’re mid-commute or preparing for a long drive. This warning signal, part of your vehicle’s Tyre Pressure Monitoring System (TPMS), is designed to alert you to a potential safety issue. Ignoring it could lead to poor fuel economy, uneven tyre wear, or even a dangerous blowout. This article breaks down the possible reasons the TPMS light comes on, how to troubleshoot it, and simple maintenance tips to help prevent future alerts.

What Does the Tyre Pressure Monitor Light Mean?
The tyre pressure monitor light—usually an amber icon that looks like an exclamation mark inside a horseshoe—activates when one or more tyres are significantly under-inflated. This system uses either direct or indirect sensors to track the air pressure in your tyres. When pressure drops below the recommended threshold, your car’s computer sends a signal to activate the light.

Common Reasons the TPMS Light Comes On
Several factors can cause your tyre pressure warning light to turn on:

• Low Tyre Pressure: The most common reason. Seasonal temperature changes, especially during colder months, can cause pressure to drop.

• Puncture or Slow Leak: A small nail or road debris might cause a slow air leak that eventually triggers the warning.

• Overinflated Tyres: Too much air can also set off the sensor, although it's less common.

• Faulty TPMS Sensor: Sensors can wear out or malfunction, especially if your vehicle is older or the sensors have been exposed to corrosion.

• Changing Tyres or Rims: If you recently replaced your tyres or wheels, the sensors might need to be reprogrammed or reset.

• Dead Sensor Battery: TPMS sensors are powered by batteries that usually last 5–10 years. Once they die, the system can’t read your tyre pressure.

What to Do When the Light Turns On
If your tyre pressure light appears while you’re driving, here’s what you should do:

1. Find a Safe Place to Stop: Pull over safely and visually inspect your tyres for any signs of deflation or punctures.

2. Check Tyre Pressure with a Gauge: Use a digital or manual tyre pressure gauge to measure PSI (pounds per square inch) in each tyre. Compare it with your car manufacturer’s recommended level (usually found on a sticker inside the driver’s door or in the owner’s manual).

3. Inflate or Deflate as Needed: If the pressure is too low or high, adjust accordingly at a service station or with a home inflator.

4. Look for Obvious Damage: Cuts, cracks, or embedded objects may indicate a puncture or leak that needs professional repair.

How to Reset the Tyre Pressure Monitor Light
After correcting your tyre pressure, the warning light might remain on. To reset it:

• Drive for a Few Minutes: Most systems recalibrate automatically once the vehicle is moving.

• Use a Reset Button: Some cars have a TPMS reset button located near the steering wheel or under the dash.

• Check the Owner’s Manual: Procedures vary by vehicle make and model.

• Visit a Mechanic: If the light stays on after you’ve checked and adjusted the pressure, a faulty sensor or programming error may be to blame.

Preventing Future TPMS Alerts
Proper maintenance is key to keeping your tyre pressure monitor light off and ensuring road safety:

• Check Tyre Pressure Monthly: Use a reliable gauge to monitor PSI, especially during seasonal changes.

• Rotate Tyres Regularly: Helps ensure even wear and consistent pressure readings.

• Inspect Tyres for Damage: Look for wear patterns or punctures that might lead to slow leaks.

• Keep TPMS Sensors Clean and Functional: If your mechanic offers a TPMS check during service, take advantage of it.

• Replace Sensor Batteries When Needed: Especially after 5–7 years, even if the light hasn’t come on yet.

FAQs

Why is my tyre pressure light on but my tyres look fine?
Sometimes the pressure difference is subtle and not visible to the eye. Always check with a pressure gauge to confirm.

Can I drive with the tyre pressure light on?
You shouldn’t ignore it. While it might not be an emergency, low pressure can reduce traction and fuel efficiency, and eventually lead to a tyre blowout.

How do I know if a TPMS sensor is faulty?
If your tyres are properly inflated but the light remains on, or if you recently had tyre work done, a faulty or unprogrammed sensor might be the cause.

Do I need to replace TPMS sensors when getting new tyres?
Not always, but it’s a good opportunity to check their condition and replace worn ones if needed.

Is it expensive to fix TPMS issues?
Replacing a sensor typically costs between $50–$100 per tyre. A full diagnostic at a shop may be necessary for persistent issues.

Final Thoughts
The tyre pressure monitor light is more than just a dashboard nuisance—it’s a vital part of your car’s safety system. Whether it’s a quick fix like adding air or something that requires professional service, understanding how your TPMS works can save you money and reduce the risk of driving hazards. Regular pressure checks, seasonal awareness, and basic tyre maintenance go a long way in preventing unwanted surprises on the road.