The submarine operated against the Royal Navy during the Falklands War without any noticeable success, but survived a number of anti-submarine sweeps carried out by British frigates.

San Luis was struck in 1997 after an incomplete overhaul; as of 2020, its hull remained stored at Domecq Garcia Shipyard (Tandanor).

[4] San Luis served in the Falklands War (Spanish: Guerra de las Malvinas/Guerra del Atlántico Sur) of 1982.

After Santa Fe was damaged, captured and scuttled by the British during the re-taking of South Georgia on 28 April, and the nuclear submarine HMS Conqueror had sunk the cruiser ARA General Belgrano on 2 May, the Argentine fleet retired to port for the duration of the war, with the exception of San Luis, making her the only Argentine naval presence facing the British fleet.

San Luis reported firing a German-made SST-4 torpedo, on purely passive sonar detection of British gas turbine-powered warship(s) and Sea King helicopters searching.

San Luis had adopted the World War II tactics of German U-boats and rested on the bottom[11] some distance from the area of interest to the British frigates, where it shut down.

[citation needed] The Royal Navy never detected or located the submarine,[14] which was in among the fleet,[15] but whose weapon system effectiveness had been limited by British Intelligence.

San Luis detected the two ships and fired two SST-4 torpedoes, one of which did not leave its tube; the other was apparently defeated by Arrow's anti-torpedo measures.

This meant that when the torpedoes' gyros were spun up, they ran "backwards" and thus tumbled on launch, preventing the weapons from taking up their proper heading.