Tire Pressure Warning Lights

This little story is something you should know about if you have a 2009 or newer car. Tire pressure warning lights have been mandated since 2009 and they have been sometimes troublesome since their inception.

I had a tire warning light come on in my car just a week ago. I looked in the manual and it said to check the tires visually and to check the air pressure in them. My tires are low profile as most cars have and they did not show any signs of low inflation. I used a 12 volt tire pump with a built in gage to check the tires. The gage showed 30 pounds of pressure in the tires. The driver’s door panel stated they should be 32; so I put two more pounds of pressure in each tire. The manual showed after a low warning light I needed to drive the car at 20 plus mph for at least 2 minutes to reset the warning light. I did that, but the light persisted.

The next step was going online to see what Google had about these issues. I watched several videos on tire pressure warning systems and they were all similar. One mentioned that in 2013 the systems changed, apparently for the better. All of them stated that during cold weather tire pressure can drop 1 psi for each 10 degree drop in temperature. We had a big cold snap right before I got the warning light. All videos said to use a good gage to check the tires. While they recommended using a high quality digital gage, three of the four videos continued to use the old-fashioned metal pressure gages like people used years ago. That fact triggered a thought. I went back out to the car and pulled out my old tire gage I bought when I worked in a gas station 55 years ago. I checked my tires with it and all were measuring 25 pounds of pressure, while the tire pump gage still registered 32. Tire warning systems are set to trigger the warning light when pressure drops 25%, and that was enough to trigger the warning in my car. I pulled out the pump and ran the pressure up to 40 pounds on its gage and then checked my old gage and they showed 32 pounds on the money.

I put my tools away and got in the car to drive it around the block to reset the sensor. I started the engine and the light went out right away, problem solved! It saved me a trip to the Ford garage and a few dollars to boot.