Airlines from the US to South America, Europe, India and New Zealand warned the repairs could potentially cause flight delays or cancellations.
The world's largest A320 operator, American Airlines, said some 340 of its 480 A320 aircraft would need the fix.
It said it mostly expected these to be completed today with about two hours required for each plane.
Other airlines said they would take planes briefly out of service to do the repairs, including Germany's Lufthansa, India's IndiGo and UK-based easyJet.
Colombian carrier Avianca said the recall affected more than 70 per cent of its fleet, prompting it to close ticket sales for travel dates through December 8.
There are around 11,300 A320-family jets in operation, including 6,440 of the core A320 model, which first flew in 1987.
Four of the world's 10 biggest A320-family operators are major US airlines: American Airlines, Delta Air Lines, JetBlue and United Airlines.
Chinese, European and Indian carriers are also among the jet's biggest customers.
For about two-thirds of the affected jets, the recall will result in a brief grounding as airlines revert to a previous software version, industry sources said.
Still, that comes at a time when airline repair shops are already overrun by maintenance work, as hundreds of Airbus jets have been grounded due to long waiting times for separate engine repairs or inspections.
The industry also has labour shortages.
"The timing is definitely not ideal for an issue like this to arise on one of the most ubiquitous aircraft around the (US) holidays," Mike Stengel of AeroDynamic Advisory said.
But due to the quick repair time, many jets can be fixed between scheduled flights or during overnight checks, he added.
Britain's easyJet said it had already completed the work.
A senior airline industry source, however, said sequencing the repairs at a time when demand is high and fleets are already facing maintenance delays was expected to be a major challenge.
Aviation analyst Rob Morris said there were questions over how much hangar capacity would immediately be available.
