A Takata airbag after a crash.

Honda is launching a major national advertising effort to convince buyers to repair millions of vehicles equipped with potentially deadly airbags produced by beleaguered Japanese supplier Takata.

So far, at least five deaths – all in Honda vehicles – have been linked to the problem in which the airbags may inflate too aggressively during a crash, sending shrapnel flying into the passenger compartment.

The campaign is meant to “to save lives and prevent injuries,” said John Mendel, executive vice president of the automobile division of American Honda Motor Co.

The suspect Takata airbags were used by 10 automakers, though Honda was the supplier’s largest customer. Collectively, the problem has become one of the largest, in terms of total vehicles involved, in automotive history.

Last year, the National Highway Traffic Safety Administration issued an unusual order covering millions of vehicles used in areas of high humidity, such as the Gulf Coast, where the bags were considered more likely to malfunction. But subsequent research, and additional fatalities, led NHTSA to call for the recall to be expanded nationwide.

(Click on image to enlarge.)

Takata has so far refused to do so, insisting the demand isn’t backed up by sufficient data. That has left automakers like Honda, Toyota and BMW to expand the recalls on their own. So far, 20 million vehicles sold worldwide are impacted.

(Toyota announces two new recalls. Camry power steering failures could increase risk of crashes. Click Here for the story.)

Repair rates for recalls, overall, average only around 70%, according to federal data. And a shortage of parts has complicated the Takata service action. But with replacements increasingly available, Honda decided to remind the public of the risks and the need to act. It says it wants “Honda and Acura owners to immediately check for open recalls and safety improvement campaigns, and to take affected vehicles to an authorized dealer for free repair as soon as possible.”

The focus of the various recalls is on the inflators that are instantly ignited in the event of a severe crash, creating the hot gases that fill airbags, creating a cushion to absorb impact forces. Takata has acknowledged that errors made at two of its North American plants apparently created an unusually volatile propellant used in some of its airbag systems.

Some safety experts, including Clarence Ditlow, director of the Center for Auto Safety, also believe that the chemical formula used by Takata is particularly prone to problems as it ages. One possibility is that the solid propellant charge begins to break down and flake, which could cause it to inflate more aggressively than intended.

A consortium of carmakers has hired an outside firm, Orbital ATK, to conduct further tests on the Takata airbags.

It is unclear if other manufacturers will follow Honda’s lead, but the industry, as a whole, has been coming under pressure to try to boost the rate of recall repairs. According to vehicle tracking service CarFax, there are 10s of millions of vehicles currently on the road with one or more unrepaired defect covered by a safety recall.

A new proposal before the U.S. Congress would, if enacted, bar owners from registering vehicles that have not had all repairs completed.

(Nissan expands Altima recall, adds another 640,000 vehicles. Click Here.)

Honda faced a record fine last year from the National Highway Traffic Safety Administration for delaying mandated reports on crashes which included a number of fatalities.