What the TPMS Warning Light Means
The tyre pressure monitoring system (TPMS) warning light — that orange horseshoe shape with an exclamation mark — means one or more of your tyres is significantly below the recommended pressure. It's been mandatory on all new cars sold in the EU and UK since 2014, and it exists to prevent exactly the kind of dangerous situations that under-inflated tyres cause.
The light triggers when tyre pressure drops roughly 25% below the manufacturer's recommended level. That's a substantial drop — by the time the light comes on, your tyre is already meaningfully under-inflated and your handling, braking, and fuel economy are all compromised.
Step 1: Don't Ignore It — Check Your Pressures Immediately
This is the most important step and it takes 5 minutes. Drive carefully to the nearest petrol station with an air pump, or use a home tyre pressure gauge if you have one.
Where to find your correct pressures:
- Sticker inside the driver's door jamb (most common location)
- Inside the fuel filler cap
- Vehicle owner's manual
- Often printed on the tyre placard in the boot near the spare wheel area
Check all four tyres — and the spare if you have one. Inflate any low tyres to the recommended PSI. The light should clear after driving a few miles at normal speed.
Step 2: Light Still On? Here's Why
If the light stays on after inflating to the correct pressures, there are several possible causes:
- Slow puncture: One tyre is losing air gradually — you inflated it but it's already leaking again
- Faulty TPMS sensor: The sensor's battery has died (they last 5-10 years) or the sensor is damaged
- TPMS needs resetting: Some vehicles require a manual reset after inflating — check your owner's manual
- Temperature change: Cold weather drops tyre pressure. A cold snap can trigger the light even on correctly-inflated tyres
Step 3: Flashing Light? That's Different
Pay attention to how the light behaves:
- Solid light: Usually means low pressure in one or more tyres
- Flashing light that then stays solid: Indicates a TPMS system fault — the sensor itself is failing
A flashing TPMS light means you can't rely on the system to warn you about future pressure drops. Your tyres might be fine right now, but you've lost your early warning system. Get the sensor replaced.
Why Correct Tyre Pressure Matters — The Numbers
Running tyres 20% under-inflated causes:
- 15% reduction in tyre life — they wear out faster, costing you money
- 3% increase in fuel consumption — that adds up over thousands of miles
- Increased braking distances — especially dangerous in wet conditions
- Higher blowout risk — under-inflated tyres overheat, and overheating is the leading cause of blowouts
- MOT failure — significantly under-inflated tyres can fail an MOT
How Often Should You Check Tyre Pressure?
Monthly. At minimum. Tyres naturally lose 1-2 PSI per month even without punctures. Cold weather accelerates this — tyre pressure drops approximately 1 PSI for every 10°F (5.5°C) temperature drop. A tyre that was perfect in September can be dangerously under-inflated by December without you noticing.
Get into the habit of checking pressures every time you fill up with fuel. It takes 5 minutes and could save your life — or at least save you the cost of premature tyre replacement.
TPMS Won't Reset? We Can Fix That.
If your TPMS warning light won't clear despite correct pressures, the sensor likely needs replacing. Main dealers charge a premium for this. TyreBlitz mobile TPMS service diagnoses and replaces faulty sensors at your location — no garage trip, no call-out fee.