TPMS repairs are becoming a more frequent service with every passing day.
TPMS, short for Tire Pressure Monitoring System, are found on many cars these days. They have been legally required on all cars sold in the US since 2008. In Canada there is no legal requirement to sell cars with TPMS systems, however, many cars come equipped with the system.
There are two types of TPMS systems: Indirect and Direct.
Indirect systems use the ABS wheel speed sensors to determine if tire pressures are too low. Generally a tire that is under-inflated will be rotating at a different speed than its fully inflated counterparts. Although this system works fairly well it is more prone to errors than the direct system. Within the last few years several European manufacturers have come out with very accurate indirect TPMS. One advantage of this system that it is less complex and has fewer parts to fail.
Direct systems have a sensor in each wheel which sends data via radio signal to a computer module. . The data contains the tire’s pressures and temperatures and the driver is alerted if the pressure drops below a preset threshold. Because the pressure inside the tire is measured directly, this system is the most accurate.
A disadvantage of direct TPMS is that the sensors are battery powered and batteries have finite lives. The general lifespan of a TPMS sensor is about 7 years. Batteries cannot be serviced separately: once the battery dies so too does the sensor.
Sensors can be purchased from the vehicle manufacturer or dealer, but a more cost effective solution comes from the aftermarket. Universal sensors are available for most vehicles and these can be specially programmed to your vehicle. OEM sensors also involve programming. Anytime a new sensor is installed it must inform the TPMS computer of its ID number so that it is recognized as part of the vehicle.
While TPMS add complication and added repair expenses it is very worthwhile. First off, you no longer need to physically check your tire pressures. Most motorist know that this should be done monthly but how many do it (almost no one). Secondly, under inflated tires waste a huge amount of fuel, according to the US Department of Transportation they estimate that under inflated tires waste 2 billion US gallons (7,600,000 m3) of fuel each year. 2 Billion gallons! That’s alot of gas, a lot of money, a lot of greenhouse gases; and all for nothing!
If your TPMS warning light is on, your first step is to check and adjust your tire pressures. If it remains on then the system needs to be diagnosed and repaired.
For more about TPMS history and operation please click on this link http://en.wikipedia.org/wiki/Tire-pressure_monitoring_system