At 10.28 hours on 16 February 1942 the unescorted and unarmed Monagas (Master Walter James Bushell) was hit on port side aft in the engine room by one G7e torpedo from U-502 about 12 miles west of Punta Macolla in the Gulf of Venezuela. The tanker stopped and only settled slowly by the stern, so the U-boat fired a second G7e torpedo as coup de grâce at 10.42 hours. The torpedo was aimed at the foward part, but struck on the port side aft underneath the funnel due to a gyro malfunction and broke the back of the ship. The U-boat then left to attack and sink the San Nicolas nearby.

The burning Monagas developed a heavy list and was later investigated by the Venezuelan gunboat ARV General Urdaneta (Capt Tomás Mariño Blanco), which rescued two survivors and brought them to Las Piedras, but the drifting wreck continued to burn for three days and eventually sank after stranding 4 miles north of Punta Espada, Guajira. The remaining survivors had been picked up by the Dutch steam tankers Rosalia and Ramona, arriving at Maracaibo one day later.