The Citizens Utility Board and the Illinois Attorney General are warning Nicor Gas customers about a service they call “overpriced and rarely used.”

Nicor offers the so-called Gas Line ComfortGuard for the inspection and repair of potential gas leaks inside homes.

CUB Executive Director David Kolata said more than than 400,000 people are enrolled in the program, which costs $4.95 a month, “but only 2 percent of customers covered by ComfortGuard ever needed their pipes repaired, so the program is guarding against problems that almost never occur.”

And Kolata said an average repair costs consumers less than what they pay for ComfortGuard annually. He said the the average cost of a repair for a non-ComfortGuard customer in 2009 was $47, compared to ComfortGuard’s $59.40 annual price tag.

The ComfortGuard service covers in-home repairs up to $600 per incident. But Kolata said less than 3 percent of gas-leak repairs made by Nicor for non-ComfortGuard customers were more than $100.

In a statement, Attorney General Lisa Madigan said, “Nicor’s ComfortGuard service does not live up to marketing promises that it will save money for consumers. Consumers looking for comfort should carefully review their gas bills to determine whether they really need to pay an extra $4.95 a month.”

Nicor is legally obligated to investigate reports of gas leaks and, if necessary, shut off the gas for free.

CUB and the Attorney General’s office are urging the Illinois Commerce Commission to consider Nicor’s profits from the service as utility revenue. That could mean Nicor could be required to lower the cost of gas for consumers.

In a statment, Nicor said it disagrees with CUB’s claims. They say the Gas Line ComfortGuard protects the safety of its customers at a great value.