How to Troubleshoot a Tire-Pressure Monitoring System (2023)

How to Troubleshoot a Tire-Pressure Monitoring System (1)

When this warning lamp illuminates on your instrument panel, at least one of your tires is 25 percent below its correct pressure. This TPMS sensor uses a lithium battery with a five- to 10-year life span. But you still need to keep a decent tire gauge in your glovebox.

It's hot. Real hot. Fortunately, the new car you bought right before that Arizona spring-break road trip has air conditioning that works great, in spite of the heavy pop-up trailer and loaded roof rack weighing it down. You pull in for gas and lunch, and carefully check the pressure in the trailer tires with the gauge that lives in your glovebox. The tires on your crossover are fine though, because all new cars have a tire-pressure monitoring system that will tell you if your tires are low from the comfort and safety of your driver's seat. The desert beckons, and 40 miles of heat-shimmered asphalt later, a tire blows. What happened?

After swapping in the spare, you continue your trip at a more sedate pace. The TPMS light is on, and you stay well under the speed limit until you can check the tire pressures with a gauge. Surprise--they're all low. Surprise No. 2: The TPMS light remains on after you top off the tires to the correct pressure, at least until you can get a replacement tire mounted later in your trip.

Be Prepared

A Department of Transportation study dating back to 2001 says that 60 to 80 percent of cars on the road are running tires underinflated by as much as 10 percent. Worse yet, they say that 20 to 50 percent are being driven with tires down in pressure by as much as 20 percent. Yet, here's the scariest part: If your tires are low, even falling into that minus 20 percent category, your TPMS won't tell you--ever. The TPMS warning light is only required to illuminate when the pressure gets 25 percent below the correct value, which is enough to reduce fuel economy, lower the available grip (especially in wet conditions) and make tires run substantially hotter.

(Video) Finding Failed TPMS Sensor

Bottom line: Don't trust the TPMS. Once you understand how your TPMS system works, you'll understand why it doesn't obviate the need for regular tire-pressure monitoring.

The Easy Way

There are two types of TPMS on the market, direct-reading and indirect. Indirect systems use only software and readouts from the individual wheel-speed sensors used by the antilock brake system. If all four tires are properly inflated, they will all rotate the same number of revolutions in a stretch of road. If one tire rotates more than the other three, it has a shorter rolling radius because the pressure in it is low.

The indirect type of system is inexpensive, because the only real part that must be added to a car is the display on the dash and some extra code in the vehicle's operating system. Properly inferring tire pressures this way can be a problem when the tires are unevenly worn, or if you replace only two worn tires instead of all four. You can reset the system to allow for wear when all the tire pressures are correct. The procedure varies from vehicle to vehicle, and this one won't necessarily work on yours. Persistent TPMS warnings can often be cured by setting the tire pressures properly and then resetting the TPMS somewhere in the menu on the driver's display, or perhaps with a scan tool. If the system isn't reset this way, TPMS warning lights will also crop up after a normal tire rotation, or if you're replacing tires with ones of a different size from the old ones.


How to Troubleshoot a Tire-Pressure Monitoring System (2)

(Video) WHY Your Tire Light is ON & EASY FIX

1. TPMS senders are usually attached to the valve stem, although some are banded to the wheel's drop center. These units can cost over $100, but replacements for most domestics can be found on the aftermarket for $50 or less. They're prone to damage from tire-mounting machines, so get your tires mounted by a knowledgeable technician.

2. In an attempt to reduce the sensor's mass and keep the wheel in balance, the metal stem of the sender is commonly made of aluminum. Soft aluminum. Use a torque wrench on the inch-pound scale to tighten these, because it's really easy to strip the threads by overtightening. Ferrous-metal valve caps may interfere with the electronics, so stick with OEM-style plastic valve-stem caps.

How to Troubleshoot a Tire-Pressure Monitoring System (3)

The Better Way

There is a much better (read: more expensive) technology to monitor tire pressures. Higher-end vehicles use a direct-reading system of battery-powered senders mounted inside the tire, communicating with the TPMS by means of small antennas in each wheel well. Every few minutes, the TPMS will interrogate the senders in the wheels, acquire a "true" pressure reading and transfer the message to the in-car display.

But what's to keep the system from reporting the tire pressure of the car next to you at a traffic light? In order to keep things straight, the individual senders have a unique serial number to transmit to the vehicle. And that keeps individual wheels on each corner of the car properly sorted in the TPMS's tiny little brain. On many vehicles, there's even a sender on the spare tire. The TPMS is initialized with the position of the four (or five) tires when the car is new. Eventually, those tires could change position, through normal tire rotation or as the result of a flat. That's why there is a procedure to resynchronize the system. For most vehicles, it involves the use of a special tool that communicates with the vehicle and the sender to make everybody play nice. This device knows which wheel is which because it's held next to each valve stem in turn as the system is programmed. Your car dealer will have one, and some independent repair shops might as well. Unfortunately, they're different for every brand of car, and they cost plenty, with basic models going for $600 to $800, and those that work on a variety of vehicles running up to $2500.

(Video) How to replace & register TMPS tire pressure monitoring system sensors on Toyota, Lexus, Scion cars

Fortunately, it's rarely necessary to use the factory-style tool. Each manufacturer has its own tool and procedure. Look in (surprise!) the owner's manual.

And all of this has to happen within 2 minutes, or the learn mode times out and you'll have to start over. Also, if anyone nearby is adjusting tire pressures on a car with TPMS sensors, the system may be confused. If your vehicle's TPMS includes the spare, burrow into the trunk and get access to the spare first. Don't forget to top off the tires to the correct pressure.


How to Troubleshoot a Tire-Pressure Monitoring System (4)

1. The definitive correct tire pressure is on this sticker on the door frame. This info is also in the owner's manual. Ignore what's printed on the tire sidewall. Your car manufacturer has determined what pressures will make your car handle properly. The pressure on the sidewall is the maximum pressure for any vehicle.


2. Tire pressure should be checked in the morning on cold tires, not after you've driven to Starbucks. Tire pressure changes 1 psi for every 10 degrees of outside temperature. A change from 70 F to 40 F will lower the pressure 3 psi, enough to affect wet braking and fuel economy; check your pressures monthly.

On some GM cars you can activate the wheel sensors with a simple, powerful horseshoe magnet. GM has a special tool for this, but I'll bet a nice strong magnet from RadioShack would work. On Toyotas, apparently the only way to activate the sensors is with the Toyota TPMS tool or scan tool. Your mileage may vary. You'll need to find out exactly what procedure your vehicle needs any time you rotate tires or install winter tires. Consult your owner's manual, or the factory service manual. Be wary of advice on TPMS from enthusiast websites: A lot of the procedures I saw there were wrong or just plain out-of-date.

Special Considerations

If you ever need to replace a valve-stem core, use stainless steel rather than brass to avoid corrosion. It's one thing to replace a $2 rubber valve stem and something else entirely to replace a $100 TPMS sensor. And always use that cap. Water, road salt or mud could affect the sensor.

One last thing: That can of aerosol flat-fixer in your trunk may damage the sensor. Yes, it says "Sensor Safe" on the label, but experience in the field says it's a bad idea. The hole-filling compound may well plug up the hole in the sensor that checks pressure. If you must use one of these products, take the vehicle to a properly trained tire technician as soon as possible to have the hole plugged properly from the inside.

Here's a typical procedure for teaching the TPMS system which wheel is which:

1. Place the ignition switch in the "ACC" position.

2. Simultaneously press the keyless entry transmitter's lock and unlock buttons until a horn chirp sounds. This will put the system in "learn mode."

(Video) BMW 2007 Tire Pressure Monitoring System. Fixing the tire warning light.

3. Starting with the left front tire, increase/decrease the tire pressure for 5 to 8 seconds, then wait for a horn chirp. The horn chirp may occur before the 5-to-8-second pressure increase/decrease time period has been reached, or up to 30 seconds after the 5-to-8-second pressure increase/decrease time period has been reached.

4. After a horn chirp has sounded, proceed as in step 3 for the next three sensors in the following order: right front, right rear, left rear.

5. After the LR sensor has been learned, a double horn chirp will sound, indicating that all sensors have been learned.


Why is my tire pressure monitoring system not working? ›

The problem could be a damaged or shorted antenna near the wheel, or a wiring fault between the antenna and the module. If you suspect the TPMS module is not receiving a good signal from one or more sensors, check the antenna wiring for continuity and problems such as shorts, opens or high resistance.

How do I know if my TPMS is bad? ›

Signs You Might Need To Replace Your TPMS Sensor
  1. Dead Batteries. The TPMS sensor relies on your car battery in order to work properly. ...
  2. Alerts Must Be Wrong. TPS sensors might provide misleading information if they are malfunctioning. ...
  3. Increased Fuel Consumption. ...
  4. Handling Concerns. ...
  5. Shoddy Tire Change.

How do you reset the tire pressure monitor sensor? ›

With the vehicle off, turn the key to the “On” position, but do not start the car. Hold the TPMS reset button until the tire pressure light blinks three times, then release it. Start the car and wait about 20 minutes for the sensor to refresh.

Where is the tire monitor reset button? ›

The tire pressure monitor reset button is typically located under the steering wheel. Refer to your vehicle's owner's manual if you're unable to locate it. Inflate all tires to 3 PSI over their recommended amount, then deflate them completely. Be sure to include the spare tire, as it may have a sensor as well.

How can a properly functioning TPMS sensor become damaged? ›

The valve stems of some TPMS systems operate in salt, water and ferrous brake dust. These elements can damage a sensor over time. Galvanic corrosion can kill a sensor from the inside.

How much does it cost to replace a TPMS sensor? ›

TPMS Replacement Costs and What to Expect

In the event TPMS sensors need to be replaced, the cost can range from approximately $50-$100 each depending on vehicle type.

Do TPMS sensors go bad? ›

Generally, TPMS sensors should be replaced when needs it first set of tires, or after 5 to 7 years or 60,000 to 80,000 miles.

Can I replace just one TPMS sensor? ›

If one of your TPMS sensors fails and needs replacement, you can replace it individually. However, if the failure was caused by a dead sensor battery, it's likely that the other sensors are close to failing as well.

How many years do TPMS sensors last? ›

Home How long should a TPMS sensor last? TPMS sensors run on batteries that can last anywhere from 5-10 years. Sensor battery life will depend on how much driving you do over time and the conditions that you drive in.

How do you test a tire monitor sensor? ›

The pressure reading from a sensor can be easily verified by checking the actual pressure in the tire with a gauge. If the pressure value displayed on your TPMS tool from a sensor reads 32 PSI (or whatever), you should find 32 PSI when you check the pressure with a gauge.

How do I reset my TPMS sensor without the tool? ›

Resetting Your Tire Pressure Light

Attempt to reset the TPMS sensor by driving at least 50 mph for 10 minutes. The next time you turn the car on, the light should be off. Start the battery on your car, but not the ignition.

Do TPMS sensors need to be reset? ›

If you have an indirect TPMS system, your mechanic will need to manually reset the sensors after changing your tires. If you have a direct TPMS system, no additional maintenance is required to reset the system. A new TPMS system will typically last for about 10 years before the batteries run out.

Where is TPMS fuse? ›

The sensors in the wheels... TPMS FUSE NUMBER ? The tire pressure warning system fuse is located in the fuse box located under the dash, just to the left of the steering column.

Why does my car say low tire pressure but tires are fine? ›

If the tire pressure warning light on your dashboard remains on after a long while, it's an indication that one or more of the tires is leaking air. If the TPMS warning light flashes on for 1 second, then off for 3 seconds repeatedly, this is an indication that the vehicle has issues with one or more of the sensors.

Why is my TPMS sensor light on but my tires are fine? ›

Worn-out Wheel Sensor

The wheel sensor that works with your tire pressure sensor can get worn or damaged if your wheels aren't balanced properly. If the wheel sensor is faulty, the TPMS light will come on when you turn the car on, just as it does when your tire pressure is too low.

What happens if you don't replace TPMS sensors? ›

What Happens If You Don't Replace TPMS Sensors When Required? If you neglect to replace worn out tyre pressure sensors, they will not work as they should and they will not be able to properly monitor the inflation of your tyres.

Can you replace battery in TPMS sensor? ›

Most of them last about 7-10 years -- less if you do a lot of stop-and-go driving, because the sensors only send their signals to the car's computer when the car is stopped. When the battery finally does die, it can be replaced.

How do I know if my TPMS sensor is working? ›

The easiest way is to watch the dashboard indicator lights at start-up. Turn the vehicle's ignition switch to the "ON" or "AUX" position, or simply start the vehicle. Look for a TPMS warning light on the dashboard.

Is it worth it to replace TPMS sensors? ›

A: Tire pressure monitoring sensor batteries are designed to last 10 years. It sounds as though yours may have died. The law does not demand that you replace the sensors, but for your peace of mind, convenience and safety's sake, it makes sense to replace them.

Can a tire shop replace TPMS? ›

Sometimes, a TPMS alert means one or more of the TPMS sensor batteries has died. In this situation, you may need to replace the TPMS sensor. All of our store locations can perform these replacement services for you.

Where is the TPMS sensor located? ›

Where is the tire pressure sensor located? It is inside the tire attached to the inner part of the rim. If you remove the tire from the rim, you'll see a small cylinder, which is the tire pressure sensor.

Do you have to replace all TPMS sensors at once? ›

Tips for Proper TPMS Service

If a single sensor has reached the end of its lifespan, it is highly recommended to replace all sensors at the same time. Similar to headlights, once one sensor dies, the rest are likely to be close behind. The same is true for a corroded valve stem or other non-impact sensor replacement.

Can Autozone relearn TPMS? ›

The MaxiTPMS TS408 is an easy-to-use handheld TPMS service tool that can activate and read sensor IDs, battery life and tire pressure and temperature. The TS408 can also program MX-Sensors to replace OE sensors and can display on-screen relearn procedures for all TPMS-equipped vehicles.

Will disconnecting the battery reset TPMS? ›

Can I Disconnect the Battery to Clear the TPMS Sensor? Some people try to clear codes by disconnecting the battery. Generally the system saves all codes and doesn't reset them just because the battery is removed.

How often do you need to replace a TPMS sensor? ›

TPMS sensors are designed to last for many years – 5-10 years is a likely lifespan. Given their cost, most drivers will be inclined to replace TPMS sensors on an “as needed” basis – in other words, only once their batteries have expired, or other TPMS components have failed.

Can I drive my car with the TPMS light on? ›

It's not safe to drive around with your TPMS light illuminated. Without a tire inspection, there's no way of knowing how quickly air is leaving your tire, or for how long it has been over or underinflated. The best course of action is to use a tire pressure gauge to check the current inflation level of each tire.

Can you drive with a faulty tire pressure sensor? ›

If you don't replace your faulty tire pressure sensor, you run the risk of driving over something and puncturing your tire. If this happens, it may be difficult to tell that you have a flat because the low air pressure warning should have already been triggered but is not being displayed on your dashboard.

Can tire pressure sensors be repaired? ›

SImple. The Ken-Tool reCore kit provides everything you need to drill out the corroded valve core, tap new threads, and install a new, corrosion-proof valve core and stem. No need to have the TPMS computer re-learn the module. No need to even remove the tire or wheel from the vehicle!

Is there a fuse for tire pressure sensor? ›

The tire pressure warning system fuse is located in the fuse box located under the dash, just to the left of the steering column.

Will a tire pressure sensor reset itself? ›

Once your tires are at the appropriate pressure, the light may go off on its own. If it doesn't go off right away, driving at 50 mph for about 10 minutes should help the tire pressure sensor reset.

How much does it cost to service a tire monitor system? ›

You can expect to pay between $50 and $100, which includes the labor cost. It depends on whether or not they can change the TPMS sensor without taking the whole wheel off. Most cars don't let you do this, but if you have one that lets you change the TPMS sensors without taking the tire off, you'll probably pay less.


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