The incident occurred at the Sepang International Circuit after heavy rain delayed the start by around 40 minutes.
When the formation lap eventually began, a number of cars encountered problems while travelling at low speed, with some coming to a complete stop on track.
The race start was delayed again as the FIA worked with the teams to identify the problem and introduce a fix across the grid.
The investigation focused on four main areas: identifying the exact cause of the power losses, finding ways to prevent a repeat, reviewing wet-weather power unit settings and analysing data supplied by the teams and power unit manufacturers.
The FIA has now confirmed that the issue was linked to the software controlling the power units under the unusual conditions experienced at Sepang.
It has also clarified comments made after the race by FIA single-seater director Nikolas Tombazis, who said the software had not been tested in the conditions encountered in Malaysia.
According to the FIA, the software had undergone simulation testing before being introduced and was also tested during full-scale running in Free Practice 1 at the Belgian and Dutch Grands Prix.
However, the investigation identified the need for more extensive testing and stronger validation procedures.
The FIA said measures would be introduced to improve software testing, despite the limited opportunities to replicate extreme wet-weather conditions during race weekends.
The governing body will work with the teams and power unit manufacturers to strengthen software verification, including independent assessment and feedback from the supplier of Formula 1’s standardised electronic control unit.
For this weekend’s Singapore Grand Prix, the power units will revert to the configurations used in Malaysia if similar wet-weather conditions occur.
A further software update is then planned for the United States Grand Prix in Austin.
The next round takes place at Singapore’s Marina Bay Street Circuit from 9 to 11 October, with another Sprint weekend on the schedule. Sprint Qualifying and Free Practice 1 take place on Friday, the Sprint and Grand Prix qualifying are on Saturday, before Sunday’s Grand Prix.
