A steady TPMS light means at least one tyre is genuinely low on pressure — check all four with a gauge, including the spare on some systems. A light that flashes for 60 to 90 seconds after starting the car, then stays on solid, is a different signal entirely: it usually means a sensor or system fault rather than low pressure. The flashing pattern is the detail most people miss.
Steady vs Flashing — The Distinction That Matters
Most TPMS systems use two distinct light behaviours, and mixing them up leads people to keep adding air to tyres that were never low in the first place.
| Light behaviour | What it means | What to do |
|---|---|---|
| Comes on and stays steady | Genuinely low pressure in at least one tyre | Check and correct all four pressures |
| Flashes for 60–90 seconds at start-up, then stays solid | System fault — a sensor, battery or receiver problem | Needs diagnosis, not air |
| Comes on only in cold weather | Normal pressure drop with temperature, usually genuine | Check and correct pressures |
| Comes on after changing a wheel or tyre | A sensor may need relearning to the new position | TPMS relearn procedure |
| Never comes on, but a tyre is visibly low | Possible dead sensor battery | Sensor diagnosis |
1. Genuinely Low Pressure
The straightforward and most common cause. Tyre pressure monitoring exists specifically to catch this before it becomes a handling or safety issue, and a steady light deserves to be taken at face value.
Check all four tyres with a proper gauge — do not rely on how a tyre looks, since modern low-profile tyres can be significantly under-inflated without appearing visibly flat. Compare against the figure on the door sill or fuel flap sticker, not the number moulded into the tyre sidewall, which is a maximum rather than a recommendation.
Remember that pressure drops roughly 1 psi for every 10°C fall in ambient temperature, so the first cold snap of autumn is a very common time for this light to appear across an entire fleet of otherwise unremarkable tyres.
2. A Slow Puncture
If one tyre keeps needing air every week or two while the others hold steady, that consistent pattern points at a slow puncture rather than general seasonal pressure loss.
Check for: a visible nail or screw, a puncture repair kit’s telltale plug already in place from a previous fix, or a valve stem that has perished and is leaking at its base. A soapy water spray around the tyre and valve, watched for bubbles, finds most slow leaks without needing to remove the wheel.
3. A Failing TPMS Sensor
Each wheel typically has a small battery-powered sensor mounted inside, either attached to the valve stem or as a separate band around the wheel. These sensors have a finite battery life — commonly 5 to 10 years — after which the sensor itself needs replacing, not just the valve or the tyre.
Recognise it by: the flashing-then-steady pattern described above, or a TPMS reading that shows an implausible value (0 psi on a tyre that is clearly fine, or a reading that never changes regardless of actual pressure) rather than a genuinely low but plausible number.
Fix: $60 – $150 per sensor, though many workshops recommend replacing all four at once if they are all of similar age, since if one has failed from age the others are likely close behind.
4. Needs a Relearn After Wheel Work
Many systems associate each specific sensor with a specific wheel position, and that association can be lost after a tyre rotation, a wheel change, or fitting a spare. Some cars relearn automatically after a short drive; others need a specific relearn procedure — sometimes through the infotainment menu, sometimes requiring a dedicated TPMS tool at a workshop.
Recognise it by: the light appearing specifically after wheel-related work, with pressures confirmed correct on all four tyres.
Fix: often free if it is a self-relearn procedure you can do from the driver’s seat — check your handbook for the exact steps, which vary significantly by manufacturer.
5. A Spare Tyre or Non-Monitored Wheel
If a spare has been fitted temporarily, many systems either show a specific spare tyre warning or simply cannot read a position that has no sensor at all, and the light stays on until a monitored wheel is refitted.
Similarly, aftermarket wheels fitted without transferring or replacing the sensors will trigger a permanent fault, since there is nothing there to read.
How to Check It Yourself
- Check all four pressures with a gauge, cold, against the door sill figure.
- Note the light’s behaviour at start-up — steady from the moment you start the engine, or a flash-then-steady pattern.
- Look for a per-wheel pressure display if your car has one — many modern systems show individual tyre pressures through the trip computer, which immediately tells you which corner (if any) is actually low, or whether all four read plausible but the light is on regardless (pointing at a system fault rather than a tyre).
- Check the spare if your system monitors it — an overlooked spare is a common, easily-missed cause.
Can You Keep Driving?
Yes. This is an informational warning rather than a stop-driving fault. Correct any genuinely low pressure promptly, since underinflation affects handling, fuel economy and tyre wear, and increases blowout risk at speed — but the light itself is not something that requires pulling over immediately.
The one exception worth a more careful check: if the light suddenly changes from flashing to steady, or a specific tyre pressure reading drops rapidly while driving, treat that as a genuine and possibly fast-developing puncture rather than a routine seasonal top-up.
When to See a Mechanic
Worth a workshop visit if:
- The light shows the flashing-then-steady pattern, indicating a system fault.
- Pressures are all correct but the light stays on regardless.
- One tyre repeatedly needs topping up faster than the others.
- A relearn procedure through your car’s own menu has not resolved it after a wheel change.
More in our dashboard warning lights section and our guide to reading uneven tyre wear patterns, since pressure problems and wear patterns are closely related.
Frequently Asked Questions
What does it mean if the TPMS light flashes then stays on?
That specific pattern — flashing for 60 to 90 seconds at start-up, then staying solid — usually indicates a system fault rather than low pressure, most often a failing sensor. Adding air will not fix this pattern.
Why does my TPMS light come on in cold weather?
Tyre pressure drops roughly 1 psi for every 10°C fall in temperature, so a tyre correct in warm weather can genuinely read low once it turns cold. This is normal and the fix is simply to correct the pressure.
How long do TPMS sensors last?
Typically 5 to 10 years, limited by the internal battery, which cannot be replaced separately — the whole sensor needs replacing once it fails.
Why is my TPMS light on after I changed my tyres?
Many systems need a relearn procedure to associate each sensor with its wheel position after tyre or wheel work. Check your handbook — some cars relearn automatically after a short drive, others need a specific procedure.
Can I drive with the TPMS light on?
Yes, it is informational rather than a stop-driving fault. Check and correct tyre pressures promptly though, since underinflation affects handling, economy and blowout risk.
