Warning-light wink has drivers in dark

January 23, 2003|By Jim Motavalli | Jim Motavalli,NEW YORK TIMES NEWS SERVICE

It's a tiny rectangle hidden among the gauges clustered on the dashboard near the steering wheel. When all is well, it is blank and quiescent. But then one day, unaccountably, it glows yellow and commands, "Check engine."

Drivers are trained to respond to orders of this sort. When a light flashes "Low fuel," they hurry to a gas station. When a tiny indicator speaks of inadequate oil pressure, they add oil. But "Check engine"? Especially when, as is usually the case, the engine shows no obvious signs of doing anything but humming along contentedly?

How to check it? And what to check?

All cars sold in America since 1996 are equipped with a new generation of check-engine lights, but America doesn't seem to know why. Respondents to a small, unscientific e-mail and phone survey show what appears to be national confusion about the meaning of the check-engine light.

"Aargh," wrote Carl Frankel, a computer consultant from Kingston, N.Y. "I haven't a clue! The shame, the horror."

Jennifer Kaylin, a free-lance writer who lives in New Haven, Conn., said: "I don't have the faintest idea what the check-engine light means. I guess you should slam on the brakes, pull over and dial a service station."

Mary Witkowski, a librarian in Connecticut, believes strongly that the check-engine light signals a blown fuse, but only in Hondas. "Two other people I know with Hondas have had the same experience," she wrote.

A retired Kentucky banker, Bob Stoess, sees a message of approaching misfortune clear enough to serve as a metaphor: "Let God be your check-engine light," he wrote on the inspirational Web site Hangtough.com. "We need a light to come on in our minds to help us avert conflict, pain or disaster."

Valerie Richardson of Bridgeport, Conn., a graphic designer, remembered panicking when the light appeared. "I thought it meant the engine would be ruined forever if I drove another foot," she said.

But as many drivers know, it wouldn't have been. After the fear and panic of the light's first flash, the driver who doesn't rush to a dealer usually notices as the days pass that nothing at all seems to be awry.

As it happens, that isn't true. The light may mean many things. A frequent problem, for example, is that the emissions system is off kilter, and the car is polluting the air; another is that the gasoline cap is loose, causing the car's computer to detect an unusual pressure level in the tank. (Tighten it and the light will eventually go off).

But glitches that activate the check-engine light are often nothing a driver would notice. As a result, the country is full of people driving around with check-engine lights aglow -- often while trying to figure out how to shut them off.

A cottage industry has grown up around that shut-off problem. Some mechanics advertise, "Check-engine lights disconnected." Online marketers hawk $200 reset tools. And Charlotte Kidd, a horticulture writer in Philadelphia, is probably not alone in her solution: She keeps the glowing check-engine light in her 1988 Subaru covered with black tape.

The check-engine light, formally known as a malfunction indicator lamp, is an indication of a failure somewhere, and the problem is often related to emissions. If the catalytic converter or oxygen sensor is defective, the level of pollutants coming from the tailpipe may have soared.

Your car's computer is constantly checking information from engine and transmission sensors against data stored in its memory. When one of hundreds of potential faults is found, the check-engine light comes on, and the computer records a trouble code that can be read only with expensive computerized diagnostic equipment. This system favors the service departments of auto dealerships, often the only places in town where those tools can be found.

Bob Frankston, a computer engineer and a creator of the VisiCalc spreadsheet program, renowned as the first "killer app" software, felt helpless when his check-engine light came on. "I was annoyed at what I consider the simple refusal to share information with me," he wrote in an e-mail recently. "It's like replacing a temperature gauge with an idiot light."

Car owners' growing tendency not to take the check-engine light seriously and auto mechanics' acts of sabotage to disable it are both predictable responses to mystifying messages. But since emissions problems are so often the cause, the result is that a lot of cars are doing a lot of polluting. This has not escaped notice in California, where the fight against air pollution is constant. A 2001 state law requires that carmakers make emissions-related service information available to all approved mechanics.

Cars sold in the United States after 1996 have standardized software called OBD-II (On-Board Diagnostics) to identify problems and switch on check-engine lights. But carmakers use four different computer protocols for retrieving data from car computers. And studies have shown that OBD-II software makes mistakes.

An alternative? There are handheld OBD-II scan tools that give some information and turn the light off, but they are expensive and not for the average driver.

Carmakers could replace the cryptic "Check engine" message with a specific readout. For example: "Bad heated oxygen sensor. Estimated cost of repair $200 to $400. OK to drive the car for a few days until you can get to a repair shop." But they show no inclination to do so.

Frankston, the programming expert, isn't willing to wait. He said he would rather see a digital interface that made information available to amateurs who could design their own systems for analyzing the computer data.

But many people still have trouble programming VCRs, let alone designing software for analyzing engine problems. The next time the check-engine light comes on, they will probably just reach for the black tape.

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