Washington ? Automakers agreed Thursday to give independent repair shops their closely guarded codes used to diagnose troubles with today’s high-tech vehicles so the shops can make the same repairs as franchise dealerships.

The fault or diagnostic codes, which appear on a handheld computer that the mechanic attaches to the vehicle to designate the source of trouble, were long withheld from independent shops because automakers said they feared the information would be misused by unscrupulous mechanics.

For instance, the anti-theft system code could be used to break into similar vehicle models, and the air bag system code could be used to secretly install a fake air bag and sell the real one to another customer.

Some automakers felt more comfortable giving the information to their dealerships, which must keep the data confidential under franchise contracts. That often meant higher costs to consumers, since dealer labor rates tend to run $10 to $20 per hour higher than independent shops, according to AAA.

The Automotive Service Assn., which represents 13,000 independent repair shops, said 15 percent of repairs could not be performed because of unavailable codes, resulting in an annual loss of $18 billion to the industry.

“This deal should eliminate that loss,” said Bob Redding, the association’s lobbyist. He said repairs should be quicker and less expensive since independent mechanics will not have to send vehicles to the dealer for those services.

Pat Slimmer, owner of Slimmer’s Auto Service, 2030 E. 23rd St., praised the agreement Thursday.

“It is great news,” Slimmer said. “Probably the toughest part about repairing a modern car is having the right information. We don’t have all the information that dealer technicians have, and that is a problem. We’re not on even footing, and this should change that.”

Under the agreement signed by the Automotive Service Assn., the Alliance of Automobile Manufacturers and the Association of International Automobile Manufacturers, the automakers agree to make the information available on the Internet by Aug. 31 at a “reasonable price.” It will be available to all professional mechanics as well as amateurs working out of their garage, said Charlie Territo, spokesman for the Alliance of Automobile Manufacturers.