If you’ve seen a little yellow horseshoe-shaped warning light appear on your dashboard, that’s your Tyre Pressure Monitoring System (TPMS) trying to tell you something important.

Here at St. George’s Tyres, we often see drivers confused or worried when their TPMS light comes on — especially during colder months. Here’s everything you need to know about how TPMS works, what the law says, and why temperature changes can affect your tyre pressures.

What Is a TPMS and Why Is It Important?

A Tyre Pressure Monitoring System (TPMS) constantly checks the air pressure in your tyres while you drive. If it detects that one or more tyres are under-inflated, it alerts you with a dashboard warning light.

Keeping your tyres correctly inflated helps with:

•  Safety: Properly inflated tyres improve handling and braking.
•  Fuel efficiency: Under-inflated tyres increase fuel consumption.
•  Tyre life: Even tyre pressures prevent premature wear and blowouts.

Your TPMS is there to keep you safe and save you money – so it’s worth paying attention when it warns you something’s wrong.

How Does a TPMS Work?

There are two main types of systems fitted to vehicles in the UK:

1. Direct TPMS

Each wheel has a small electronic sensor that measures air pressure inside the tyre. These readings are sent wirelessly to your car’s onboard computer. If pressure drops too low, your warning light comes on.

2. Indirect TPMS

Instead of using pressure sensors, indirect systems use the car’s ABS wheel speed sensors to detect changes in wheel rotation. A slightly deflated tyre spins faster than the others, triggering the alert.

Most modern cars use direct TPMS, as it’s more accurate and gives instant readings.

TPMS and the Law in the UK

TPMS is not just a convenience feature — it’s a legal requirement on newer cars.

• Since November 2012, all new passenger cars sold in the UK and EU must be fitted with TPMS.
• From January 2015, a faulty or malfunctioning TPMS became a MOT failure item.

So, if your TPMS light is on, it could cause your vehicle to fail its MOT — and more importantly, it means your tyres might not be safe.

Why Does My TPMS Light Come On in Cold Weather?

It’s common for drivers to see the TPMS light appear on cold mornings — especially during autumn and winter around Sandy and Biggleswade.

That’s because cold air contracts, which lowers tyre pressure (around 1 psi for every 10°C temperature drop). Your TPMS picks up this small pressure drop and turns on the warning light.

Here’s what to do:

1. Check your tyre pressures when they’re cold (before driving).
2. Inflate to the manufacturer’s recommended settings (usually on a sticker inside your door frame or in your handbook).
3. Once corrected, the light should go off automatically.

If it doesn’t, or if it keeps coming back, visit us — we can inspect and reset your system properly.

Common TPMS Problems

Over time, TPMS sensors can develop faults. The most common issues include:

•  Sensor battery failure (usually after 5–10 years)
•  Damage during tyre replacement
•  Corrosion or water ingress
•  Non-compatible aftermarket wheels or valves

At St. George’s Tyres, we have the tools and expertise to diagnose, replace, and reprogramme TPMS sensors for all makes and models.

Don’t Ignore That Warning Light!

Driving with incorrect tyre pressures affects your safety, fuel economy, and comfort. Even a small drop in pressure can lead to:

• Longer braking distances
• Reduced grip — especially in wet or icy conditions
• Faster tyre wear
• Risk of blowouts at motorway speeds

Your TPMS is there to protect you — so don’t ignore it.

If your TPMS warning light is on, or you’re unsure whether your system is working correctly, pop in to St. George’s Tyres.

We’re located right on the A1 southbound between Sandy and Biggleswade, making us the perfect stop for local motorists and fleet drivers in Bedfordshire, St Neots, Biggleswade, Sandy and the surrounding areas.

Our expert technicians can:

 Check and reset your TPMS

 Replace faulty sensors

 Reprogramme TPMS systems for any make or model

 Advise on the correct pressures for your vehicle

We’ll make sure your tyres — and your TPMS — are in top condition so you can drive safely and efficiently all year round.

 Find us on the A1 Southbound between Sandy and Biggleswade

Call us today on 01767 681297 or book your TPMS check online for friendly, professional tyre care you can trust.