Leclerc had been in contention to score some points at the Circuit de Barcelona-Catalunya before his engine cut out after hitting a kerb in the final sector, causing him to spin.
While Leclerc was able to get back to the pits and have his seat belts re-tightened after not expecting to rejoin the race, Ferrari opted to retire the car, later citing an electrical issue as the cause of his retirement.
The team has announced ahead of this weekend's Belgian Grand Prix that it has identified the cause of the electrical problem that forced Leclerc out of the race in Spain, denying him the chance to score some points.
"In this first part of the season we have seen the championship pretty much divided into two groups: on the one hand, three drivers who seem to be uncatchable and on the other, another ten or so all within a few tenths of one another," said Ferrari head of power unit Enrico Gualtieri.
"In Barcelona, we paid a high price for a lack of reliability, and in fact we have now identified the problem with the electronic control unit that caused Charles' retirement.
"But we also suffered from not maximising our qualifying performance, which put us in a difficult situation in the race.
"Aware of the current difficulties, we have to focus on our work in preparing for the weekend. The main aim is to ensure the drivers can get the most out of the SF1000.
"We must optimise the car-PU package, work well in the garage, define the best strategy and be efficient when it comes to reacting to changing conditions."
Leclerc would be free to take a new control electronics element for his power unit for Belgium without receiving a penalty, as he is still within the season limit of two parts.
Ferrari is braced for a difficult weekend at the Circuit de Spa-Francorchamps given the power-sensitive nature of the circuit.
The team has struggled with the straight-line speed of its SF1000 car throughout the season so far, causing it to fall away from Mercedes and Red Bull at the front of the pack and instead drop into F1's midfield fight.
Leclerc took his maiden grand prix victory in the Belgian Grand Prix last year, but is braced for a far tougher race this weekend.
"In terms of expectations, it will be tougher for us in terms of performance this time around as we do not have the same level of competitiveness as we did in 2019," Leclerc said.
"However, we have seen that anything can happen at this track, especially with the unpredictable weather.
"As a team, we will have to work very hard to do all we can to get the most out of the car right from Friday.
"In free practice, we must gather all the information needed to pick the best strategy for qualifying and especially for the race."