Detonator and Warhead: Mod 0 featured an impact fuze, but mod1 also added magnetic fuze, since test showed that seekers winding path could make the torpedo hit target at a sharp angle preventing the contact detonation.
The only Argentine operational Type 209 submarine, ARA San Luis (S-32), fired three torpedoes with no hits after all of them failed to work properly.
Investigations conducted by Argentine Navy after the conflict came to the results that there was a problem in the seekers who were assembled wrong, and with the support of the manufacturer fixed the entire navy SST-4 supply in the next years, further upgrading them by the addition of magnetic fuze, performing a successful live test in which the newly commissioned ARA Santa Cruz (S-41) sunk the decommissioned destroyer ARA Py (D-27) on June 15, 1987.
In 2018 the Turkish navy destroyed a target ship with a SST-4 Mod 0 fired from the TCG Yildiray.
[citation needed] In 2020 the Hellenic Navy destroyed a target ship with a SST-4, fired from the Υ/Β ΠΙΠΙΝΟΣ 214 HN (S121).