British regulators investigating the fire on a Boeing 787 Dreamliner identified the plane's emergency locator beacon as a likely source of the blaze.
They have asked that the component be switched off on all Boeing 787's until further notice.
The findings spurred a rally in shares from relieved investors.
Boeing said the beacon could be removed in about an hour from its newest model plane, which was grounded for more than three months earlier this year due to a battery issue.
Regulators said this earlier event was unrelated to the fire on an Ethiopian Airlines jet in London a week ago.
The US Federal Aviation Administration regulations do not require the transmitter, but some other nations do, the manufacturer said.
A European regulatory official said the jets could fly with the locator beacons temporarily de-activated, despite regulations mandating them in most commercial situations.
Shares in Boeing rose 2.6% to $107.40, closing in on the all-time high of $108.15, set just before the fire was reported.
The beacons, made by U.S. conglomerate Honeywell, are positioned in the upper rear part of the advanced jets, and send a signal that leads rescuers to downed aircraft.
They are powered by non-rechargeable, lithium-manganese batteries.
