What is the Horseshoe-shaped Dashboard Warning Light?
Its cold weather time again and time again to speak about the Tire Pressure Monitoring System (TPMS), and its associated warning light(s). Every year several million more drivers who have recently upgraded their cars will encounter the light for the first time.
These are two versions of the TPMS light, and either one is easily the most misunderstood warning light you’ll find on your instrument panel. And the fact that its shaped like a horseshoe doesn’t help.
First, unlike other yellow/amber lights, there is nothing wrong with your car — it presents you information about your tires and likely as not there’s nothing actually wrong with them either.
Why the Light Is On
There are two possible reasons why you are seeing this light. First, as the weather cools the most likely possibility is that all four of your tires are low on air (and/or the spare!). The second possibility is that one tire has a leak of some sort, but we’ll return to that in a moment.
Air expands when heated and contracts when cooled. Air that has cooled and contracted in your tires leads to reduced tire pressure. The warning light comes on and air needs to be added to your tires. Its important to note that air has not actually leaked out.
But the warning light does not discriminate between cooling air and actual air leaks. It comes on if one tire is low or all four is low, so more information is needed. Your model may or may not include a display option like the one shown. It is a read out of the tire pressure in the individual tires. If all four tires read roughly the same, within a pound or two, the warning light is the result of seasonal cooling.
And while on the subject, a thought for manufacturers. Every vehicle equipped with the tire pressure warning light simply must be equipped with this display. Leaving your customers in the dark by displaying the warning light only is unacceptable to us.
Now, if one tire is several pounds lower than the others, 5, 6 or 7 pounds or more, that tire is leaking and needs to be serviced as soon as possible.
If your vehicle is one that features only the warning light, the tire pressures need to be checked by hand to determine the cause — a single leak or seasonal reduction in all four.
If you’re not comfortable checking your tire pressures or with filling them, the good news is that pretty much every tire store, repair shop or car dealer will fill them for you at no cost. Its simple for them to do and they make a friend in the process, meaning more business from you down the road. Please drop in on one of them.
If you are comfortable with checking your tire pressures and adding air, by all means do so. But you will first need to know the required tire pressure. Look for a label just below where the driver’s door latches. The required pressures will be shown. They will match left to right but will likely be a little different front to rear. Set the pressure on the pump and trust it. It will stop pumping once the proper pressure is reached. You may also find yourself using a pump with a built in gauge. Trust it as well and be sure to add your spare tire to the routine.
Each tire valve has a cap that needs to be unscrewed and removed. Don’t lose it — it keeps water and dirt out and will keep the valve from developing a leak.
Learn more about this warning symbol here.
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Remember that only proper service and repair procedures will ensure the safe and reliable operation of your car. In addition, proper safety procedures and precautions, such as the use of safety goggles, the right tools and the equipment should be followed at all times to eliminate the possibility of personal injury or improper service which could damage the vehicle or compromise its safety.
These posts are for information sharing purposes only, and should not be used in lieu of an OEM service manual or factory authorized service procedure. We are not in the auto repair business nor do we publish automotive service manuals. Nothing we include on these pages and posts has been reviewed, approved or authorized by any vehicle manufacturer.
Technology is always changing and what is current and accurate today may be literally out-of-date and inaccurate tomorrow. And when it comes to the current state of flux in the auto industry, nothing is more true.
The author has 25 years of automotive experience and has assembled the most extensive collection of symbols and warning lights anywhere (over 1,000!) and can help you open and start any keyless start car with a dead key fob battery. BA, St. Joseph’s College, ME: MS, Rensselaer Polytechnic Institute, NY
In Jeep vehicles built prior to 2009 and using the rectangular-tipped key, the Engine Start / Stop button must be removed from the ignition switch for key fob use. With the ignition in the Lock position, insert the metal part of the emergency key (or a finger nail!) under the chrome button (above right) and gently pry the button loose. It comes away very easily. Note that the button itself appears to float 
just above the dash.
Do NOT try to remove this button!
Note: If you have made an attempt to start the vehicle without success, there may be residual pressure in the brake system and a new warning light may appear (left) or text message to Step on the Brake. Press the brake pedal very, very hard when trying to start the vehicle again to be sure that the release switch behind the pedal is engaged. Or wait a few minutes and try again.
Retrieving the mechanical key
The Key Fobs used in models built after 2010 are sleeker and rounded (see the image to the right) but work the same way. Slide the mechanical latch at the top of the back of the Fob to the side and pull the emergency key out with your free hand.
The 500e, e for electric, introduced in 2024, uses a new back up start method. The key fob is dropped into the cup holder between the front seats. The buttons should be facing up (right). The right spot will be marked by the image of a key with lines radiating from it.
The Key Fobs used in Fiat models built after 2010 are sleek and rounded (see the image to the right). Slide the mechanical latch at the top of the back of the Fob to the side and pull the emergency key out with your free hand. The top of the key is found next to the key ring hole.
The 500e, e for electric, introduced in 2024, uses a new key fob that hides the mechanical key inside the fob housing. The back side cover of the fob needs to be removed. Slide the cover in the direction of the arrow towards the key ring end (right). The cover can then be lifted away. The key itself is revealed and can also be lifted away (far right).
In 2023, the 500e will be hiding its keyhole behind a small cap in the handle recess (see image). The cap is easily removed with a fingernail, using the access hole shown to the right. Once removed the use the mechanical key in the keyhole to unlock the door, and you’ll be inside.
Stuck Inside?
Marc Favreau
The author has 25 years of automotive experience and has assembled the most extensive collection of symbols and warning lights anywhere (over 1,000!) and can help you open and start any keyless start car with a dead key fob battery. BA, St. Joseph's College, ME: MS, Rensselaer Polytechnic Institute, NY
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