Seeing a sudden yellow dashboard warning signal can make any driver nervous. When that glowing horseshoe-shaped icon with an exclamation mark appears, your vehicle is telling you something important about your tyres.
Understanding exactly how to react to an illuminated TPMS warning can save you from a dangerous roadside emergency, expensive tyre wear replacement cost, or an unexpected MOT failure. Whether you are driving down the motorway or navigating through Central London, knowing how to handle a tyre pressure alert is essential for your safety.
What Is a TPMS Warning Light?
A TPMS warning light is the visual dashboard fault indicator for your Tyre Pressure Monitoring System. This system constantly monitors the air pressure inside your tyres, alerting you the moment a tyre falls below the manufacturer pressure tolerance.
Usually, the system triggers a warning notification if there is a pressure drop 6–7 PSI below the optimal inflation specification, or a 25% pressure reduction overall. Ignoring this persistent warning light can lead to a severe tyre blowout risk, increased rolling resistance, reduced fuel efficiency, and compromised vehicle stability. In some cases, poor inflation can even cause a car shaking when driving.
How Tyre Pressure Monitoring Systems Work
Vehicle manufacturers use two distinct types of technology to monitor tyre pressure. Depending on your make and model, you will have one of the following systems installed.
Direct TPMS
Direct TPMS relies on a dedicated pressure sensor module mounted inside each wheel, usually attached to the valve. These sensors measure the exact pressure and temperature of the air inside the tyre. They transmit this data wirelessly to the vehicle’s central computer. Each sensor has its own internal TPMS battery, which generally lasts between five and ten years before requiring a complete sensor replacement.
Indirect TPMS
Instead of physical pressure sensors inside the wheels, indirect TPMS works alongside your vehicle’s Anti-lock Braking System (ABS). This ABS-linked TPMS uses the wheel speed sensor to measure how fast each tyre revolves. An underinflated tyre has a slightly smaller diameter, meaning it must spin faster than a fully inflated one. The computer uses this rotational variance detection to figure out if a tyre is losing air, triggering the dashboard tyre pressure light.
Why Your TPMS Light Has Turned On
A tyre pressure warning display does not always mean you have a flat tyre. Several factors can cause the light to illuminate.
Low Tyre Pressure
The most common reason for a flashing TPMS warning or solid light is simply underinflated tyres. Tyres naturally lose a small amount of air over time. If you do not perform regular pressure maintenance habits, the pressure loss threshold will eventually be crossed.
Temperature Changes
If you notice a winter tyre pressure warning on the first cold morning of the year, physics is to blame. Ambient temperature drop causes tyre contraction in cold air. The cold weather tyre pressure loss can drop your pressure just enough to trigger the sensor. Once the tyres warm up through driving, the temperature-related pressure loss often reverses, and the light may switch off.
Slow Puncture or Valve Leak
A slow puncture caused by a nail or screw can trigger a warning long before the tyre looks flat. Similarly, a leaking tyre valve or damaged valve stem can cause a slow, steady loss of air.
Faulty Sensor Battery
Direct TPMS sensors rely on internal batteries. When the battery dies or a sensor communication fault occurs, the system will usually flash for 60 to 90 seconds before staying solid, indicating a sensor fault rather than an actual pressure issue.
Wheel Seal or Rim Damage
Hitting a pothole can cause rim air leakage. A wheel seal failure or a tyre bead leak prevents the tyre from holding an airtight seal against the alloy wheel, leading to a steady drop in pressure.
What To Do Immediately When the TPMS Light Appears
If your TPMS light turns on while driving, follow this 8-step guide to protect your safety and prevent further damage.
- Stay calm and reduce speed: Do not slam on the brakes. Gently decelerate and keep a firm grip on the steering wheel, as a rapid deflation can cause poor steering response.
- Pull over safely: Find a safe place to stop, away from moving traffic.
- Consult vehicle manual: Check your handbook to find the manufacturer recommended pressure for your specific car.
- Inspect visible tyre damage: Walk around the car and look for obvious signs of a puncture, a flat tyre, or sidewall damage.
- Check pressure: Use a reliable pressure gauge inspection tool to measure the air in all four tyres, including the spare.
- Inflate tyres correctly: If you are near a petrol station, inflate the tyres to the correct level.
- Reset system: Perform a manual TPMS reset according to your vehicle’s handbook.
- Seek professional help: If a tyre is visibly flat, heavily damaged, or you hear hissing, do not drive on it. Call for a professional tyre inspection.
Why Your TPMS Light Won’t Turn Off After Inflation
Many drivers ask: why is my tire pressure light still on after filling tires?
If you have topped up the air but the tyre pressure warning light won’t go off, you likely need to perform a system reset. Some cars do not automatically detect the new pressure until you manually tell the computer to perform a recalibration cycle. Additionally, if there is a tyre pressure imbalance (where one tyre has significantly more air than the others) or a broken TPMS sensor, the warning light keeps coming back on.
How to Reset the TPMS Warning Light
Resetting the light depends entirely on your vehicle make and model. Always check your handbook first.
- TPMS reset button: Many vehicles have a physical button located in the glove box, under the steering wheel, or on the centre console. Turn the ignition on (without starting the engine) and hold the button until the light flashes three times.
- Dashboard settings reset: Modern vehicles often bury the reset option within the digital infotainment screen or dashboard settings.
- Driving recalibration method: Some systems require a TPMS recalibration drive cycle. You may need to complete a 20–25 mph recalibration drive for about 10 minutes to trigger the system relearn procedure.
(Note: Specific models have quirks. A Corsa tyre pressure light won’t go off until navigated through the indicator stalk menu, while a Dacia Duster tyre pressure warning light reset or general Dacia tyre pressure warning light reset usually requires holding a button on the end of the wiper stalk while stationary).
Can You Drive With a TPMS Fault?
You might wonder if you can simply ignore the light.
When it is safe:
If you have manually checked all four tyres with a gauge and confirmed the pressure is perfect, you can safely drive a short distance with a faulty sensor.
When it becomes dangerous:
Driving with actual underinflated tyres leads to uneven tread wear, braking inefficiency, and severe fuel economy loss. More importantly, it creates unsafe driving conditions due to reduced vehicle control.
When to stop immediately:
If you feel the steering pulling heavily, hear a flapping noise, or experience severe car shaking when driving, you are facing an active blowout or total pressure loss. Stop immediately to avoid an accident.
Will a TPMS Fault Cause MOT Failure?
Yes. According to the 2015 MOT TPMS rules, a functioning tyre pressure monitoring system is a legal requirement for all cars registered after 1 January 2012.
If your dashboard warning light stays illuminated during the test, it is a guaranteed dashboard warning MOT failure. Ensuring your sensors work is critical for meeting roadworthiness standards UK. Do not wait until your MOT to fix a broken sensor, as it will result in inflated maintenance expenses and a failed test.
When to Call Emergency Mobile Tyre Help in London
If you are stuck on the roadside with a flat tyre or a stubborn TPMS warning, Call Out Tyres is here to help. We provide 24/7 mobile tyre fitting and emergency roadside tyre diagnostics across Greater London.
If your TPMS warning light appears while driving through Croydon, Bromley, or Central London, our mobile technicians can come directly to you. We offer:
- Same-day mobile response
- Emergency roadside pressure diagnostics
- On-site tyre replacement
- Mobile TPMS fault inspection
- Roadside puncture repair
- Immediate tyre sensor troubleshooting
Whether you are in Wandsworth, Sutton, Dulwich, Purley, or Caterham, we provide a fast, reliable mobile puncture inspection and same-day tyre repair to get you safely back on the road.
How to Prevent Future TPMS Problems
Proactive maintenance prevents annoying dashboard alerts and extends tyre lifespan.
- Weekly checks: Do not rely solely on the electronic system. Check your tyres with a manual gauge every few weeks.
- Cold weather monitoring: Pay extra attention as winter approaches. Keep your tyres topped up to combat temperature drops.
- Valve inspections: Replace your valve caps if they go missing, as dirt and water can ruin the delicate TPMS sensor inside.
- Professional servicing: Ask your mechanic to run a diagnostic on your TPMS sensors during your annual service to check battery health.
Frequently Asked Questions
Why won’t my tyre pressure light go off even though pressure is fine?
If your pressures are correct, you either need to perform a manual dashboard reset, complete a driving recalibration cycle, or you have a faulty direct TPMS sensor with a dead battery that requires professional replacement.
How do I clear my tyre pressure warning light?
First, ensure all tyres are inflated to the manufacturer specification. Then, locate your vehicle’s TPMS reset button or access the dashboard menu to initiate the reset sequence. Finally, drive the vehicle at a steady speed for 10 minutes to allow the system to recalibrate.
Can I drive with a tyre pressure sensor fault?
If you have manually verified that your tyre pressures are correct using a reliable gauge, you can drive with a faulty sensor. However, you will not be alerted if you develop a genuine puncture, and the fault will cause an MOT failure.
How much does it cost to fix a tyre pressure sensor?
Replacing a faulty TPMS sensor typically costs between £50 and £150 per wheel in the UK, depending on the vehicle make and whether it requires specialised coding to communicate with your car’s computer.
Final Thoughts
A TPMS warning light is a critical safety feature designed to protect you from sudden blowouts and poor vehicle handling. Never ignore a dashboard tyre pressure light. By acting quickly, checking your pressures, and understanding how to reset the system, you maintain control of your vehicle’s safety and performance.
If you cannot clear the fault or suspect a puncture, do not take the risk of driving on it. Call Call Out Tyres for fast mobile tyre assistance anywhere in Greater London. Our on-site tyre inflation service and emergency tyre repair London experts will diagnose the issue and get you moving safely again.