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Tire Pressure Monitoring System (TPMS) Service

TPMS warns you when a tire is low — and low tires are a safety hazard, a fuel economy penalty, and a fast way to destroy a tire from the inside. Auto Care Plus diagnoses, services, and replaces TPMS sensors at our NH, MA & ME locations, including relearn and programming procedures. A TPMS light is telling you something; we find out what.

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All new cars and light trucks on the roads in New Hampshire and Maine since 2008 have come equipped with a tire pressure monitoring system, or ‘TPMS’. The TPMS system detects when a tire becomes under-inflated and lights up a warning light on the dash.

So what’s the big deal? Well, under-inflated tires can be a real safety concern for everyone. First of all, they don’t handle properly and that can lead to an accident. Second, under-inflated tires can overheat and cause the tire to come apart, which can also lead to an accident.

Government regulations requiring TPMS systems aim to reduce accidents in New Hampshire and Maine and save lives: A very worthy goal. There are also positive environmental effects because under-inflated tires are fuel wasters – you lose 1 percent of your fuel economy for every 3 pounds of pressure below ideal. So proper tire inflation can save you a tank of gas a year. And your tires last longer so you won’t have to replace them as often.

There are two kinds of TPMS systems. So-called direct systems have a battery powered sensor in each wheel that measures tire pressure. The sensor sends a signal to a receiver that illuminates the warning light if pressure is low on a tire.

Indirect systems use a computer program to detect under-inflation by measuring wheel rotation speeds and other data.

You’ll have to replace TPMS parts as they wear out. Obviously, the batteries in the sensors will run out someday. Road salt and grime can damage sensors too. The system needs to be reset when you rotate or change your tires.

Because the TPMS system is so important to your safety, you should make the necessary repairs when needed. And remember, TPMS is no substitute for regularly checking your tire pressure– at least once a month.Because the TPMS system is so important to your safety, you should make the necessary repairs when needed. And remember, TPMS is no substitute for regularly checking your tire pressure– at least once a month.

DID YOU KNOW?

Your Tire Pressure Monitoring System warning light goes off when a tire is 25 percent under inflated. If your recommended pressure is 32 psi, 25 percent below means you are at 24 psi; which is severely under inflated. At that low pressure, your safety is at risk, your fuel economy is compromised, and your tire is wearing out too fast. Check your pressure at least once a month.

Frequently Asked Questions

Why is my TPMS light on when my tires look fine?

A tire can be significantly underinflated and still look completely normal — you generally cannot see a 20 percent pressure loss by eye. The light typically triggers at about 25 percent below the recommended pressure, which is well below safe but not visually obvious. Always check with a gauge, not by looking.

What does a flashing TPMS light mean?

A flashing TPMS light that then stays solid indicates a system malfunction rather than a low tire — usually a dead sensor battery, a failed sensor, or a sensor the vehicle cannot read. It means the system cannot warn you about a low tire at all, so it is worth diagnosing.

Do TPMS sensors have batteries that die?

Yes. TPMS sensors have a sealed, non-replaceable battery that typically lasts five to ten years. When it dies, the sensor must be replaced — there is no way to recharge or service it. This is the most common reason for a TPMS fault on an older vehicle.

Why does my TPMS light come on in cold weather?

Air contracts as it cools. A drop of about 10 degrees Fahrenheit costs you roughly one PSI. A New England cold snap can easily drop tire pressure enough to trigger the light overnight. Set your pressures when the tires are cold, to the door-placard specification.

Do I need new TPMS sensors when I buy new tires?

Not always, but it is often the right time. If your sensors are approaching the end of their battery life, replacing them while the tire is already off the wheel saves you the labor of dismounting it again later. At minimum, we replace the valve stem service kit — seals, cores, and nuts — with every tire installation.

Can I just ignore the TPMS light?

We would not recommend it. Underinflated tires wear out much faster, hurt fuel economy, increase stopping distance, handle poorly, and can overheat and fail catastrophically at highway speed. The system is there for a reason. A TPMS fault will also fail a state inspection on vehicles subject to it.

Can you turn the TPMS light off without fixing it?

We will not do that. The light is a safety warning, and disabling it without fixing the underlying issue leaves you with no warning the next time a tire goes low. We would rather find out why it is on.

Signs you need this service:

  • TPMS warning light illuminated on the dash
  • TPMS light flashing then staying on (this indicates a system fault, not low pressure)
  • Light stays on after you have correctly inflated all tires
  • Tire pressures reading incorrectly or not at all on the display
  • One tire consistently losing pressure
  • Light comes on every cold morning and goes off later
  • You just had new tires installed
  • Sensor battery has reached end of life (typically 5-10 years)

Our process:

  • Read the actual tire pressures and compare them to the door-placard specification
  • Inspect all tires for punctures, valve leaks, and bead or rim seal problems
  • Scan the TPMS system and read each individual sensor's ID, pressure, and battery status
  • Determine whether the fault is low pressure, a failed sensor, or a system or receiver fault
  • Review findings and provide a written estimate
  • Repair any tire leak or replace the failed sensor
  • Program the new sensor to the correct ID for your vehicle
  • Perform the TPMS relearn procedure so the vehicle recognizes each sensor position
  • Set all pressures to specification and verify the light is out
  • Confirm accurate live pressure readings on the dash display

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