ANDERSON, S.C.-The growing number of states requiring enhanced emission testing continues to send motorists scrambling to automotive service shops in search of that elusive fix that will produce a passing grade for their vehicles. In some cases-and hundreds of dollars later-they're still searching.
Thanks to federal Environmental Protection Agency (EPA) clean air mandates, shops equipped to handle the specialized repairs have been able to tap into what has become for some a lucrative business.
Passing an ``E-test'' can often be as close as an engine tune-up away, but one often overlooked, yet essential, part needing replacement in a tune-up is the vehicle's oxygen sensor, according to the Robert Bosch Corp.
As auto engines become more and more computerized, oxygen sensors play an increasingly crucial role in monitoring engine exhaust, one of the most common causes of air pollution, said officials of the Broadview, Ill.-based automotive component manufac-turing and marketing company.
The oxygen sensor-mounted in the ex-haust manifold-continually monitors exhaust gases and, via electrical leads, signals the engine computer to adjust the air/fuel ratio. This ensures that gasoline combustion is as complete as possible, thus reducing harmful emissions while improving engine performance and fuel efficiency.
On an April 2 Bosch-sponsored tour of its Anderson plant, which produces 95 percent of all the oxygen sensors the firm sells in the U.S. aftermarket, trade journalists and automotive writers were briefed about these components and observed firsthand how their failure can affect vehicle performance.
The company provided data it called the most comprehensive ever compiled-from a 1994 EPA study and a 1990 analysis by the California Air Resource Board-that found between 66- and 70-percent of the vehicles tested for emission problems needed a new oxygen sensor. Both agencies used different testing and vehicle methodologies, but nevertheless reached the same conclusions. The second-most prevalent emission repair needed was a new catalytic converter.
Bosch, which invented the oxygen sensor in 1976, claims a new sensor will increase a vehicle's fuel efficiency by 10 to 15 percent, while reducing surging and hesitation and protecting against premature catalytic converter failure.
Although it sold 3.1 million sensors in 1995, Bosch estimated that is only 28 percent of the number that should be replaced. This year the company expects to produce its 100 millionth sensor.
While these sensors have been standard equipment on vehicles since 1980, Bosch said a 1990 survey showed 99.7 percent of all consumers did not know their vehicle had an oxygen sensor, much less how much it can affect driveability.
According to Chuck Ruth, general product manager, engine management and safety products at Bosch's Anderson facility, two-thirds of all vehicle emissions test failures are a result of worn out oxygen sensors.
The company produces a variety of sensors for original equipment vehicle manufacturers, and also sells the units on the aftermarket to a number of warehouse, jobber and installer outlets including Firestone auto service centers.
Bosch said oxygen sensors range in price from about $25 for the older, non-heated variety, to heated sensors averaging $40-$50 or more. Some newer vehicles have more than one sensor. Life expectancy for the sensor also varies-from about 25,000 miles for the low end sensors, to 100,000 miles.
Mr. Ruth called the sensors ``routine maintenance items'' and an important part of an engine tune-up. They also should be considered a top culprit when a motorist complains of dwindling vehicle fuel economy or poor performance, he said. In lieu of OBD II (onboard diagnostics) and enhanced emission testing, he urged increased technician education about the sensors.
Techs can check the units' operation with various electronic instruments, including an oscilloscope or digital meter.
The benefit for service shops and the aftermarket, Mr. Ruth said, is an increase in preventive maintenance work and higher sales of emissions parts and service.
Customers need to be reassured, he said, that ``. . . when the oxygen sensor is degraded, you can very quickly recoup its low replacement cost from the fuel savings of up to $100 a year resulting from complete combustion and a smoother running engine.''