My Tire Pressure Light Came On – What It Means and What To Do

You’re cruising along without a care in the world when suddenly an ominous orange tire pressure warning light pops up on your dash. “Uh oh, now what?” you think. At best it’s annoying, at worst it could signal real trouble with your tires. Take a deep breath and don’t panic yet – this comprehensive guide breaks down everything you need to know about that cryptic tire pressure monitoring system (TPMS) warning light.

Here’s a quick answer:

The tire pressure monitoring system (TPMS) light indicates one or more of your tires are significantly underinflated, which can be dangerous. So check and inflate them as soon as possible, even if you have to drive for a short distance to reach a safe place to pull over. If the light remains on after refilling tires, reset the TPMS system. If it still won’t go off, have your tires and system thoroughly inspected by a qualified mechanic right away.

What is TPMS?

First things first, TPMS stands for Tire Pressure Monitoring System. This safety system uses sensors mounted inside each tire to continuously keep track of air pressure levels as you drive. The sensors transmit wireless signals to a central computer module in the car that monitors the readings. If pressure drops too low in one or more tires, it triggers a warning light on the dashboard to alert you.

TPMS technology became mandatory in all light vehicles in the United States back in 2007, right around the time flat-screen TVs and smartphones were hitting the mainstream. So unless your car is more than 15 years old, it should have the system built-in.

Why Did My TPMS Light Come On?

There are a handful of different reasons that tire pressure monitor light might be illuminated. Here are the most common culprits:

  • Underinflation – This is the primary reason TPMS lights up. It’s simply alerting you that one or more tires have low pressure. Typically the sensors light up the dash warning when air pressure drops about 25% lower than the vehicle manufacturer’s recommended inflation PSI found on the tire placard.
  • TPMS failure – Sometimes the tire pressure monitoring system components simply stop working properly. If the warning light is on but you’ve verified pressures are actually fine in all four tires, then the TPMS itself likely has an electrical issue.
  • New tire installation – When you have new replacement tires installed, the TPMS may need to be reset or recalibrated to “learn” the new sensors. Some vehicles automatically take care of this within a few drive cycles, others may need manual input.
  • Cold temperatures – Overnight cold snaps and winter weather can cause the air pressure inside tires to drop slightly thanks to basic physics. The contraction of air molecules means you lose 1 PSI for every 10 degrees Fahrenheit of temperature drop. Top them back up to the recommended inflation levels.
  • Changing elevation – Driving into mountain regions at high altitudes also impacts air pressure due to changes in atmospheric conditions. To compensate for lower air density at high elevations, your tire pressures may temporarily need a boost until you return closer to sea level.

What To Do Immediately When My TPMS Light Comes On

Seeing that tire pressure warning symbol suddenly cast a menacing glow on your gauge cluster would rightfully make anyone feel a twinge of panic. Rest assured that in most cases the light is not an immediate emergency if you’re already driving down the highway. Here’s a smart 4-step action plan for what to do next:

  1. First off, don’t panic or do anything drastic! It’s usually safe to keep driving a few more miles until you reach an appropriate place to pull over and check your tires. Unless you hear loud popping or banging noises from failing tires, avoid stopping along narrow shoulders.
  2. Take the next available exit or make your way to a safe location like a gas station or parking lot. Select a spot with ample lighting where you can easily walk around the entire vehicle while avoiding moving traffic.
  3. Turn the ignition off and locate the portable tire pressure gauge stashed in your glove box or center console. Then check the air pressure levels on all four mounted tires by unscrewing each valve stem cap and pressing the gauge tightly against the valve stem. Refer to the vehicle manufacturer’s recommended pressure levels printed on a placard normally located on the driver’s door jamb.
  4. Identify any significantly underinflated tires and use a portable inflator or compressed air source to reinflate them up to the recommended spec. Also visually inspect sidewalls, treads and any other externally visible sections for embedded nails, gashes or uneven wear irregularities.

Following the steps above will either resolve the root cause of illumination, or provide clarity if there is a non-pressure related TPMS issue needing professional attention.

How Do I Reset TPMS After Refilling My Tires?

If you topped off one more tires to the recommended pressures, you may find the bothersome TPMS warning light still taunting you from the dash. Before scheduling a trip to the mechanic or tire shop, try resetting or recalibrating the monitoring system. This simple process reboots the system’s computer brain:

  1. Make sure your ignition key is in the ON position, with the engine running or not.
  2. Locate the blue and red TPMS reset button, normally found under the steering column or inside your glovebox These buttons are specifically marked with the international TPMS symbol (which looks vaguely like a horseshoe with a triangle on top).
  3. Press and hold the designated reset button continuously for 5-10 seconds until to see the warning light blink, change colors, or flash through a specific sequence. This indicates a successful reset sequence.
  4. Next turn the ignition fully OFF for about 15 seconds, then back ON once more to complete reboot process.

The previously illuminated low tire pressure warning light should now remain off as long as all tires are inflated to adequate levels.

[Heads up: Reseting TPMS does not eliminate an existing tire pressure problem – it only wipes the current data clean! Sensors synchronize with tires during driving to provide current readings. If that pesky warning reappears shortly after a reset, it usually indicates air is still leaking from somewhere requiring repair.]


Even after getting your TPMS issue squared away, you probably still have some nagging questions rattling around up there. Here we tackle some frequently asked topics about tire pressure monitoring systems:

1. What is considered officially “low” on the pressure scale?

The thresholds vary slightly between auto manufacturers, but generally expect your TPMS low pressure warning to trigger when inflation drops about 25% below placard levels. For a typical passenger sedan with recommended pressure around 30-35 PSI, tire sensors will activate the dash light once reaching the 22-27 PSI range.

2. Is it relatively safe to keep driving with the TPMS warning symbol illuminated?

Technically yes, but this is not advisable long-term. The TPMS is trying to tell you something requires attention ASAP on your tires. Continuing to roll with underinflated rubber worsens tread abnormalities causing uneven wear issues. Stop putting additional miles on compromised tires as soon as reasonably possible. Think of the TPMS light as your tires trying to wave a giant red flag – it’s best not to keep ignoring them!

3. Why would my tire pressure warning randomly start coming on only when temps get cold outside?

Falling external temperatures often catch drivers off guard for this exact reason. The fact is colder air causes the air pressure inside your tires to drop too. Overnight cold snaps can easily siphon off a few PSI thanks simply to science and the physical contraction of gas molecules exposed to cold.

Some vehicles even have temperature-compensating sensors able to account for this effect and adjust their warning thresholds seasonally. Top off tires to the recommended numbers and the problem should disappear after the weather warms back up.

4. Will mounting a temporary compact spare donut tire trigger a TPMS warning light?

It’s possible. Most donuts tend to sit slightly underinflated from the factory. Combined with the rougher ride characteristics of their narrower shape and smaller diameter, this can confuse the TPMS computer when mixing signals from mismatched wheels. Check the spare’s inflation spec cast into the wheel itself or noted on a label. Top it off to spec and reset sensors to resolve any erroneous warnings.

5. Can I permanently disable, mute or ignore the TPMS warning light through some clever DIY hack?

Strongly advise against attempting to circumvent this important safety feature! While the intermittent light may prove temporarily annoying, remember it’s trying to call your attention to an actual tire problem needing correction. Driving any distance with underinflated, damaged or blown-out tires puts yourself and other motorists at tremendous risk. Fix the root issue (or replace faulty sensors) to restore peace of mind versus applying electrical tape over the check engine illuminator.

5. Why would air pressure drop noticeably when driving into the Rocky Mountains or other high elevation regions?

Higher ground means less air molecules are present up in the thin atmosphere. Lower barometric air pressure conditions at altitude impact tires accordingly. Expect to lose roughly 3 PSI for every 5,000 feet climbed above sea level. Accounting for this effect, vigilant mountain travelers proactively add greater pressure before ascending major passes. They then reduce back closer to normal once descending safely into lower valleys. Don’t get caught off guard by the sneaky effects of elevation underfoot!

In Closing: Decoding Your Car’s TPMS Light

Hopefully this detailed deep dive dispels some of the head-scratching mystery surrounding illumination of your tire pressure monitoring system’s warning beacon. Now that you know what TPMS is, what it does, and how to react properly when that nerve-fraying dash light appears, you can breathe easier and drive smarter.

Identifying and correcting the root trigger – whether underinflation, failing sensors, or good old Mother Nature playing tricks – gets you confidently back on the road faster and safer. Here’s to many miles of happy pressure-free motoring ahead!

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