Tyre Pressure Warning Light On? What It Means and What to Do in London

A yellow light shaped like a horseshoe with an exclamation mark has just come on. That is your tyre pressure warning light, and it usually means at least one tyre has lost air. It doesn’t always mean a puncture, but it should never be ignored. Here’s what it means, what to do in the next few minutes, and when it’s worth calling a mobile tyre fitter.

What the tyre pressure warning light means

Most modern cars have a Tyre Pressure Monitoring System, usually called TPMS. It watches the pressure in each tyre and lights up when one drops below a safe level. Your handbook will tell you whether your car has one and which type it uses.

There are two kinds of system:

• Direct TPMS uses a small sensor inside each wheel that reads the pressure itself.
• Indirect TPMS has no sensor in the wheel. It uses the ABS wheel-speed readings to spot a tyre that is spinning faster than the others because it has gone soft.

Either way, the message is the same: check your tyres.

Steady light or flashing light?

• A steady light normally means low pressure in one or more tyres.
• A light that flashes for a minute and then stays on often points to a fault with the system itself, such as a sensor that has stopped working, rather than a low tyre.

Your car’s handbook will confirm which pattern your model uses.

Is it safe to keep driving?

If the car feels normal, the steering doesn’t pull and you can’t see a tyre that is visibly flat, you can usually drive slowly to a safe place to check. If the car pulls to one side, you hear a flapping or thumping noise, or a tyre looks obviously low, stop as soon as it’s safe. Driving on a very soft tyre can damage the sidewall, and a damaged sidewall can’t be repaired.

On a busy road such as the A406 North Circular, leave at the next safe exit or turn into a side road rather than stopping in a live lane.

What to do in the next ten minutes

1. Pull over somewhere safe and switch on your hazard lights if you’re stopped near traffic.
2. Look at all four tyres. Check for one that sits lower than the others, a nail or screw in the tread, or a bulge in the sidewall.
3. Check the correct pressure on the sticker inside the driver’s door or the fuel flap. Some cars list a higher figure for a fully loaded car.
4. Don’t rely on a garage forecourt gauge alone if the tyre keeps going down. A tyre that loses air again within a day or two usually has a slow puncture.

Common reasons the light comes on

• Cold weather. Air pressure drops as the temperature falls, so the light often comes on during the first cold mornings of autumn.
• A slow puncture. A nail or screw can let air out over days rather than minutes.
• A leaking valve or a damaged rim. Potholes and kerbs can bend an alloy wheel just enough to let air seep out.
• The car has been parked for a while. Tyres naturally lose a little air over weeks.
• A faulty sensor or a sensor with a flat battery on cars with direct TPMS.
• New tyres or a pressure top-up without a system reset on cars that need one.

Can the light be reset?

On many cars the light goes off by itself once the pressures are correct and you’ve driven a short distance. Others need a reset through the dashboard menu or a button, and some need a sensor relearn with a tool.

When we come out for a tyre pressure check, we set the correct pressures for your car and relearn the sensors where the car allows it. If a sensor has failed, the light will come back, and we’ll tell you that rather than hiding it. See our tyre pressure check service for what the visit includes.

When to call a mobile tyre fitter

Call us if:

• the same tyre keeps losing air,
• you can see a nail, screw or cut in the tread,
• the tyre has gone completely flat (see our no spare wheel guide),
• you have no spare wheel, or a locking wheel nut without the key (see our lost locking wheel nut key guide), or
• you’d rather not kneel at the roadside with a pump on a dark evening.

We’re a mobile tyre service based at our shop at 189C Brent Crescent, Park Royal, London NW10 7XR. We come to your kerb, driveway or workplace, 24/7, and we’re usually with you in 15–30 minutes across London. You can also bring the car to our tyre shop in Park Royal; call first so a fitter is free.

If the tyre has a puncture in the repairable area of the tread, we repair it to the BS AU 159 standard. If it can’t be safely repaired, we’ll explain why and fit a replacement at the roadside. Not sure whether it’s a slow puncture or a flat? Read puncture or flat tyre in London: who to call. Local help: puncture repair in Park Royal, or flat tyre help in Willesden if the tyre has already gone completely flat.

Local tyre pressure checks in North West London

• Tyre pressure check in Willesden
• Tyre pressure check in Harlesden
• Tyre pressure and TPMS check in Park Royal
• Everywhere else: areas we cover

What affects the cost?

We don’t publish fixed prices, because the cost depends on what we find: a pressure check and reset, a puncture repair, or a new tyre, plus your tyre size and the time of day. Call 07466 610232 for a quote and we’ll confirm the price before we set off.

FAQs: tyre pressure warning light