Tyre Pressure Monitoring System Problems: Explained Simply, With the Maths Shown and the Caveats Stated

Tyre pressure monitoring system problems is one of those questions that sounds simple until you try to answer it for your own car. The answer depends on the car, the conditions and how you drive, so there is no single figure that fits every driver. What this page does instead is give you the method, so you can work out your own answer and know exactly what it means.

Taking tyre pressure monitoring system problems as the case in point: The sections below take the question in order: the explanation first, then the step-by-step method, then the things that can go wrong and the signs that it is time to see a professional. Every number that depends on a place or a rule states the jurisdiction it applies to, because limits change and a figure that is right in one country can be wrong in another.

What you need to know first — tyre pressure monitoring system problems

TPMS is the tyre pressure monitoring system, and its job is to warn you when a tyre loses pressure before you can feel it. Most systems work in one of two ways: direct systems have a sensor inside each wheel that measures the pressure and sends it to the car, while indirect systems watch the wheel speeds and infer a pressure loss from a tyre that is rolling slightly smaller. Both exist, both have a dashboard light, and both need the driver to know what the light means. That is the point this page works through for tyre pressure monitoring system problems.

The useful thing about tyre pressure monitoring system problems is that it can be checked with tools most drivers already own: a gauge, a tread-depth measure and the handbook for the car.

How it works in practice — tyre pressure monitoring system problems

On this page, tyre pressure monitoring system problems is the case in point: The light itself is simple: a tyre-shaped symbol with an exclamation mark, which comes on when a tyre is significantly under-inflated, or flashes when the system itself has a fault. A steady light means check the pressures; a flashing light means the system needs attention, often a dead sensor battery or a sensor that has not been relearned after a wheel change. The system is a warning, not a gauge — it tells you something is wrong, not which pressure to use, and it will not warn you about a tyre that is over-inflated.

Worked example — tyre pressure monitoring system problems

Taking tyre pressure monitoring system problems as the case in point: Take a driver covering 16,000 miles a year as an example figure. The method on this page works the same at any mileage, so the example is there to show the arithmetic, not to state a fact about your car. Start with the measurement or the figure you can check yourself — a gauge reading, a tread-depth reading, or the figure on the placard — and write it down before you do anything else. Then apply the method step by step, checking each result against the one before it, because an error early in the chain is the one that is hardest to spot later. If the result surprises you, check the inputs first: a pressure read on warm tyres, a tread depth measured in one spot only, or a figure taken from the fitted tyre instead of the placard will each give a wrong answer that looks plausible. That is why the worked example on this page states its assumptions openly, and why you should do the same with your own figures.

What changes the answer — tyre pressure monitoring system problems

Sensors have batteries that last several years and cannot be replaced separately, so a sensor with a dead battery has to be replaced as a unit. After new sensors are fitted, or after wheels are moved, the car often needs a relearn procedure so it knows which sensor is on which corner — some cars do this automatically after a drive, others need a tool or a handbook procedure. Driving without sensors is possible on some cars, but the warning light will stay on and the car will not warn you about a real pressure loss. That is the point this page works through for tyre pressure monitoring system problems.

  • For tyre pressure monitoring system problems, the point is this: Sensor type: direct systems measure pressure in each wheel; indirect systems infer it from wheel speed.
  • Battery life: sensor batteries last several years and the sensor is replaced as a unit when the battery dies. That is the point this page works through for tyre pressure monitoring system problems.
  • Relearn: after a wheel change or new sensors, the car may need a procedure to learn the sensor positions. That is the point this page works through for tyre pressure monitoring system problems.
  • On this page, tyre pressure monitoring system problems is the case in point: Warning light: a steady light means low pressure; a flashing light usually means a system fault.
  • Taking tyre pressure monitoring system problems as the case in point: Temperature: a cold snap can drop pressures enough to trigger the light, even with no puncture.
  • On this page, tyre pressure monitoring system problems is the case in point: Spare: a space-saver spare may have no sensor, so the light can stay on while it is fitted.

Common mistakes — tyre pressure monitoring system problems

  • For tyre pressure monitoring system problems, the point is this: Ignoring the light because the tyres look fine, when a tyre can be several psi low without looking flat.
  • For tyre pressure monitoring system problems, the point is this: Assuming the system will warn about over-inflation, which most systems do not do.
  • On this page, tyre pressure monitoring system problems is the case in point: Fitting new wheels without sensors and expecting the system to keep working.
  • For tyre pressure monitoring system problems, the point is this: Skipping the relearn after a rotation or a sensor change, so the car reports the wrong corner.

Step by step — tyre pressure monitoring system problems

  1. Taking tyre pressure monitoring system problems as the case in point: When the light comes on, check all four tyre pressures with a gauge when the tyres are cold.
  2. Taking tyre pressure monitoring system problems as the case in point: Top up any low tyre to the placard figure and drive a short distance to see if the light goes out.
  3. For tyre pressure monitoring system problems, the point is this: If the light flashes or stays on after the pressures are correct, the system itself needs attention.
  4. For tyre pressure monitoring system problems, the point is this: Check the owner's manual for the relearn procedure for your car.
  5. On this page, tyre pressure monitoring system problems is the case in point: Have a tyre professional test the sensors if the light will not clear.
  6. For tyre pressure monitoring system problems, the point is this: Replace any sensor with a dead battery, and have the new sensor learned to the car.

What can go wrong, and when to see a professional — tyre pressure monitoring system problems

Most problems with tyre pressure monitoring system problems announce themselves early if you know what to look for: uneven wear, a vibration that was not there before, a warning light, a noise that changes with speed, or a reading that does not match the placard. None of these is a reason to panic, and all of them are reasons to check the basics first — pressures with a gauge when the tyres are cold, tread depth across the whole tread, and the figures on the placard rather than the ones on the fitted tyre. If the basics are right and the symptom is still there, or if you find a bulge, a deep cut, a cracked sidewall or a tyre that is losing pressure quickly, that is the point to see a tyre professional rather than to keep driving and hoping. A professional can see the inside of a tyre, measure the alignment angles and test the sensors, and those are the checks that cannot be done from the driveway. The cost of an inspection is small beside the cost of a tyre worn out early or a problem found too late.

Related guides — tyre pressure monitoring system problems

Frequently asked questions

Can you drive without TPMS sensors?

For tyre pressure monitoring system problems, on many cars, yes, the car will still drive, but the warning light will stay on and the system will not warn you about a real pressure loss. You would need to check pressures manually and regularly. Some cars and some jurisdictions require the system to work, so check the rules where you drive and the handbook for your car.

What is TPMS?

For tyre pressure monitoring system problems, tPMS is the tyre pressure monitoring system. It warns you when a tyre loses pressure, using sensors inside the wheels on direct systems, or wheel-speed readings on indirect systems. It is a warning system, not a gauge: it tells you something is wrong, and you still need a gauge to set the pressure correctly.

What does the TPMS light mean?

For tyre pressure monitoring system problems, a steady tyre-shaped light with an exclamation mark means a tyre is significantly under-inflated — check the pressures with a gauge. A flashing light usually means a fault in the system itself, such as a dead sensor battery or a sensor that has not been relearned. Either way, check the pressures first.

How do I reset the tyre pressure light?

For tyre pressure monitoring system problems, first set all the pressures correctly with a gauge when the tyres are cold. Then follow the reset or relearn procedure in the owner's manual — some cars reset from a button or a menu, others relearn automatically after a drive. If the light stays on with correct pressures, a sensor may need testing.

How long do TPMS sensor batteries last?

For tyre pressure monitoring system problems, several years, commonly around five to ten depending on the sensor and the driving. The battery cannot be replaced on its own, so a sensor with a dead battery is replaced as a unit. A flashing TPMS light is often the first sign that a sensor battery has died.