The romance of trucking has always been the independence. The driver only had to think about himself, his rig, and the thousands of miles of open road.

No longer. Today, a dispatcher can watch and even control trucks as never before because semis have become sophisticated networks of sensors and wireless-communications equipment. As the driver barrels across the interstate in the flats of Montana, a dispatcher getting sensor information beamed to him via satellite may order the driver to slow down to boost fuel efficiency and reduce wear and tear on the engine. The dispatcher may relay a warning from the engine that a crippling problem is just days away, or that the temperature of the $200,000 load of perishables in the trailer is dangerously off.

Without all the information transmitted from the trucks, "our company would grind to a halt in just a few hours," says Bob Slaughter, director of information systems at Dick Simon Trucking, the fourth-largest refrigerated carrier in North America. The company has outfitted each of its 1,600 rigs with about $3,000 of hardware. "This is the future of the trucking business," he says.

And of many, many other businesses, too. Companies from auto makers to utilities, from defense contractors to health-care providers, are using remote sensors in crucial equipment to spot problems before they can occur. In the process, the companies are saving themselves and their customers time and money. In some cases, they are even saving lives.

Proponents say it's only a matter of time before such sensors become ubiquitous, even ending up in consumer appliances, to warn owners that the lawn mower needs oil or that the washing machine's clutch is about to break. "There's an unbelievable wealth of ideas coming because [the sensors] are such an intuitive concept. Once you explain what can be done, people immediately spin off ideas by the dozen," says John Nitze, an analyst at Forrester Research.

The sensors are becoming possible now because of the furious rate at which electronics are becoming smaller and cheaper. Sensors have long been used in factory equipment, where they could draw on the processing power, the databases, and the communications capabilities of the whole factory network. Now, however, all of those capabilities can be built into a tiny chip imbedded in, say, a bulldozer. The chip can listen for noises or feel vibrations, then match them against an internal database of known patterns that indicate problems. If trouble is likely, the chip can then take advantage of the spread of satellites and cellular-phone systems to call someone and sound an alarm. The sensors will keep gaining in power, too, at roughly the rate of Moore's Law, which says that a unit of computing power will drop in price 50% every 18 months and which has governed the computer industry for the more than 30 years since it was first stated.

"Increasingly, everything being made, used, or sold will have some rudimentary sensory awareness and processing capability,'' says Paul Saffo, founder of the Institute for the Future. "We're putting eyes, ears, and sensory organs on our computer networks and finally asking computers to do things that are important."

Stephen Millett, leader of the Breakthrough Center at Battelle Memorial Institute, raves: "These technologies will lead to major new benefits for consumers." Mr. Millett says they will give the companies that exploit their possibilities a three-year lead in the marketplace. He also says that the technologies will create new product lines for growth.

Imagine the possibilities. What if a car could tell its owner two weeks before an engine part was likely to fail? What if a sensor could tell a wearer to check into a hospital for assistance minutes or even hours before a heart attack was likely to occur.

Customers would love that sort of information and would happily pay for it. Whoever supplied the sensors would own the customers' loyalty for a long, long time.

The real payoff of the sensors may thus be a new, tighter relationship between companies and their customers.

Like many new technologies, remote-warning sensors are starting with mission-critical equipment. Makers of office elevators, for instance, have long used sensors that transmitted warning signals out through buildings' phone networks—Otis Elevator says it knew immediately of the extent of the 1989 San Francisco earthquake because just about all its elevators in the region reported problems simultaneously.

Much like Otis, Johnson Controls has spent the past five years building a huge library of data about how its climate-control systems perform, about early signs of trouble, and about when breakdowns occur. For example, Johnson's library contains a series of "vibration-analysis signatures" for the chillers—the huge cooling machines that power big air-conditioning systems. Johnson can now sense from afar when a building's multimillion-dollar air-conditioning system is about to fail, and intervene before it does. That saves customers tens of thousands of dollars in service costs, or some worse catastrophe, such as having a hospital lose its air conditioning.

J.I. Case's construction-equipment division is studying how sensors can predict and avoid engine breakdowns in its heavy machinery. An idle hour for one of these machines can cost an owner or lessor thousands of dollars. Case's tractor division is also adding sensors to the products it sells. Case says it has reduced daily maintenance time by a third in its MX Series Magnum tractors, which are loaded with new problem-diagnosis systems. The company's goal: to avoid costly stoppages altogether during crucial times such as planting and harvest. "As farm consolidation continues and fleet sizes grow on the average farm, there's going to be a heavier focus on up-time and making sure machines always operate at peak efficiency," says Ken Moehle, MX program manager.

Resorts operator American Skiing has outfitted each of its lifts across New England with hundreds of sensors that feed information to its computers about usage patterns, oil pressure, and other mechanical conditions so that breakdowns don't leave skiers stranded. Remote warning sensors also monitor snow conditions on each mountain, giving snow-machine operators the heads up when it's time to change the humidity settings and other parts of the snow recipe. An ideal system would turn the snow makers on and off without human supervision.

"The old-timers like to do this by the seat of their pants, getting out underneath the snow gun and just seeing what the snow looks like when it bounces off your sleeve, then adjusting," says W. Craig Alford, head of software development for mountain operations at American Skiing. "But there are too many cost ramifications to that. We need to make snow with the least amount of manipulation possible."

Utilities have become big believers in sensors because the companies have to transport gas and oil over such huge distances, often across forbidding terrain in such far-flung locales as Kazakstan or the North Sea. Some companies are now putting rugged, $50,000 sensors inside pipelines to monitor gas or oil flows and the fitness of the pumps and pipes. Information is then transmitted to a local Internet access point and sent back to the central corporate computers. "Before this, companies had to send a whole team of guys to God-knows-where to fix" any problems that affected the flow, says Mike Dager, president of Enea OSE Systems, architect of the hardware at the heart of these systems. But the problem might turn out to "just be a bug in a process-control device that can be fixed remotely. Now, they can know that" without doing a physical inspection.

Defense contractors have also become heavy users of sensors because of the expense of their equipment and because lives may hang in the balance. Researchers at TRW said they joined a research project a few years ago, hoping to slash maintenance costs for a next-generation fighter jet by developing self-diagnostic systems that could report remotely on engine problems after they occurred. "But as we got into it, we realized that if you have the kind of data that enables you to analyze where failure has occurred, the next logical step is to be analyzing that data as you're collecting it and predicting when the failure is going to occur," says Michael Drake, research engineer at the University of Dayton, a partner in the project. "If you're a pilot in combat and you're counting on full power for your vertical landing, but something is wrong with your engine and you don't know it, you're going to have problems."

While individual consumers have generally not been affected by the proliferation of sensors, that will change soon. Health-care companies, in particular, are pursuing ideas that could change the way people think about their medical care. Health-care researchers are developing batteries of sensors and transmitters that could be placed on fingers, in ears, inside toilet bowls, or just about anywhere else to remotely monitor a patient's blood pressure, changes in body fat, urine content, etc. The sensors could alert doctors of problems or simply tell patients it's time to visit a physician.

Out at the cutting edge is Medtronic, which has recently begun using a series of implantable, pacemaker-like "disease-management systems" that feed doctors warning signs of heart failure, fibrillation, and a fainting condition called syncope in patients who are at risk of repeating such troubles. Implanting the devices costs about $50,000, but, even at that price, Medtronic says the costs are far offset by the savings.

"We're really focusing on trying to prevent hospitalizations and other costly procedures, like heart operations, at this point," says Ken Riff, a Medtronic vice president. "We hope to save lives, too."

The next generation of devices may be inexpensive enough to be implanted in people identified as merely being susceptible to various problems, Mr. Riff says. As a result, the devices could help people avoid initial heart attacks and other life-threatening episodes. Indeed, some day we may all be walking around with imbedded chips monitoring our breathing and heart rates, and sending alarms to the local hospital if we enter a danger zone.

In the nearer future, such chips could curb medical costs without compromising the quality of care. "People could be sent home earlier from the hospital and avoid needless trips, if a doctor can just call up" a sensor from a remote computer and check the vital signs of a patient, says Wayne Morrison, manager of medical technology at the Oak Ridge Centers for Manufacturing Technology, a federal government research lab. "We spend a trillion dollars a year on health care. [Remote monitoring] units, when they go into mass production, would just cost a few dollars per chip. Talk about revolutionizing the industry!"

Utilities plan to add sensors to their home meters, to perform more sophisticated billing—such as charging customers different rates for their usage at different times of day. Sensors could also alert customers and suppliers to gas leaks or electric line problems before they become acute.

Johnson Controls plans to gather data for and imbed sensors in furnace motors and other devices such as home air conditioners or sump pumps, says Terry Hoffman, global products marketing manager for Johnson.

General Motors and Ford Motor already have deployed systems in some luxury models that send a cellular distress signal when a car's airbag is deployed. Now, they are focusing on predicting problems by drawing on the self-diagnostic systems that the companies long ago integrated into engine systems, to facilitate repairs even as cars became more complicated under the hood. Ford is testing systems that in a couple of years will be able to tell customers when to bring their cars in for servicing. General Motors says it has seen convincing evidence of the declining costs of its sensor-based systems and other remote technologies. Seven years ago, it built test systems and found they'd cost $2,000 per car. That price is now less than $100 per car.

Because big technology-based ideas rarely work as originally conceived, there's certainly reason to think that glitches will occur as sensors spread. There isn't a technology standard across industries yet for sensors that function as early-warning systems, so each company that wants to develop one has to go through the expense and complexity of creating its own. The basic technology isn't even bulletproof yet, given that cellular networks can have holes in them, that satellites can fail, and that sensors can get banged around in harsh, real-world environments. Bizarre problems keep cropping up, too—auto researchers, for instance, have to work to make sure that a child using a Nintendo game in a car doesn't accidentally trigger an airbag.

Even if the technology were perfect, there are plenty of more emotional issues to resolve. Liability, for one. What if a patient has a sensor implanted and it doesn't warn him of a heart attack?

Privacy has proved to be a touchy subject as companies conducting electronic commerce try to learn more about their customers. So, will those customers really want manufacturers to be able to tell how fast they drive their cars or how often they change their oil? Do patients really want their doctors to monitor every situation that sets their hearts racing?

There's also the bedrock issue of trust. If someone called and said he needed to fix a washing machine that seemed to be working fine, would the customer believe him or assume the caller was just trying to generate business?

Still, there is so much momentum behind the idea of sensors that it's hard to imagine how anything could stop them for very long. Car companies, taking a vehicle back at the end of a lease, would love to be able to know for sure that it had been maintained well. Dealers, buying a used car, desperately want to know its maintenance history. Companies in every industry are trying to improve quality, so they'd love to track the performance of their products, based on which factory or which production line manufactured them. And sensors create opportunities for efficiency everywhere—imagine if a soft-drink bottler knew exactly how many Cokes were left in a vending machine and only had to have a driver make a stop when the machine was running low.

So companies will surely keep pressing to overcome any obstacles. The technology? It'll come. It's already fairly far along. Liability? Well, the lawyers can sort that out in due time. Privacy? Companies can probably find ways to pay customers for giving up information or to penalize them for, for instance, hiding the maintenance history of a car. Trust? Companies can always provide guarantees. Johnson Controls, for instance, has a test program under which it pays a commercial customer dearly if it says an air-conditioning chiller is about to go bad, and it's wrong. "We pay for the repair if it's not bad, so it had better be," an executive says. In addition, killer apps like these sensors have a way of creating powerful, unintended benefits that overcome early problems. For instance, with sensors now going into so many tractors and linking farmers to the Global Positioning System to minimize maintenance, Case's Advanced Farming Systems thinks it can help farmers improve yields. Case is using the GPS to map how farmers' yields vary widely throughout their fields. Case then prescribes optimal fertilizer levels, row by row. "The most impressive thing to a skeptical farmer is that we can show him...that the field hasn't really been optimally farmed for generations," says Kelly Kravig, marketing manager.

With sensors in so many trucks, companies have tumbled onto an unexpected problem: The trucks are idle 50% of the time, says Mike Siegel, director of marketing for OmniTracs, a unit of Qualcomm that supplies much of the trucking industry with remote systems. Companies can now address the issue.

Dick Simon Trucking says the sensors it installed in its trucks to be more efficient wind up saving an average of one driver's life each year. Recently, a 48-year-old driver who felt queasy barely managed to pull off the road near Salt Lake City and hit a distress signal before having a heart attack. He couldn't have told anyone exactly where he was, even if he were physically capable of doing so. But his truck knew, courtesy of the GPS. The truck relayed his coordinates to a dispatcher, who got an ambulance to the driver within minutes. The driver survived.

Mr. Buss is a veteran financial journalist and principal of Veritas Communications in Detroit. He can be reached at veritascom@aol.com.