Question 1

What is a tire pressure monitoring system (TPMS)?

Accepted Answer

The TPMS systems job is to monitor the vehicles tire pressure and alert the driver if the tire pressure becomes out of range. Having properly inflated tires not only increases fuel economy and promotes good tire wear, but it also makes your vehicle safer going down the road.

Question 2

What are the different types of TPMS?

Accepted Answer

There are two main types of TPMS systems used in vehicles. Direct TPMS systems and Indirect TPMS systems. Direct systems utilize an electronic sensor inside each wheel, usually connected to the valve stem. These sensors measure the air pressure inside of the tire and send that information to the module in your vehicle responsible for monitoring and alerting you of a tire pressure issue. The second type of system doesn�t use battery powered TPMS sensors, instead of reading tire pressure directly it works off your vehicles wheel speed sensors. The system reads the wheel speed of each tire and uses this information to calculate tire pressure. A tire with low air pressure will be slightly smaller in diameter and therefore be rotating at a slightly higher speed, while an over inflated tire will be larger in diameter and will be rotating at a slightly lower speed.

Question 3

What causes the tire pressure light to come on?

Accepted Answer

The most common cause of a TPMS warning message is a leaking or under inflated tire. There are several ways a tire can lose air, like a puncture from a nail or corrosion on the rim or valve stem. Another common cause for a tire to lose air pressure is a drop in outside temperature. The TPMS light will also come on when your vehicle detects a malfunction within the system. Most direct system malfunctions are caused from faulty TPMS sensors. Indirect systems can be more of a challenge because the tire pressure is being calculated and is relative to the wheel diameter. In an indirect system a warning light may illuminate if your tires are mismatched in size or have uneven tread wear. Rotating or replacing your tires can also trigger a TPMS light if the system is not reset after service.

Question 4

How do I fix a TPMS light?

Accepted Answer

The first step is to check the pressure of all your tires including the spare. Make sure the tires are set to your vehicles tire pressure specifications which are normally located on a sticker in the driver�s door jamb, do not rely on the pressure labeled on the tire itself. Any leak over a few PSI should be further investigated or taken to a shop for repair. After you have your tire pressures set correctly, check your owner�s manual for TPMS warning light information and reset procedures. If you are unable to complete the relearn or reset procedure a system malfunction most likely exists, and further diagnostics are needed.  Systems can be diagnosed with specialty tools that can read and trigger TPMS sensors along with full function scan tools to read and interpret vehicle data or trouble codes. Once the proper repairs have been made, the warning light will be able to be reset using the vehicles designed relearn or reset procedure.