What was found
AFTER LEVEL OFF AT FL340 A RED BOX AROUND ENGINE INSTRUMENTS ILLUMINATED. OIL PRESSURE INDICATION ON #1 ENGINE INDICATED 0 AND THE LOW OIL PRESSURE LIGHT FOR #1 ENGINE ILLUMINATED. RAN QRH AND RETURNED TO KDEN. / [01] REF FIM 79-05 TASK 803 INSPECTED OIL TANK SCREEN WITH NO DEFECTS NOTED.;[02] REF TSR 2022008895 INSP MCDS AND OIL PRESSURE SENSOR CP?S WITH NO FAULTS NOTED;[03] REF AMM 73-21-60 R&R #1 EEC;[04] REF TTG8Q00GBDH4 AND WORK PREFORMED ABOVE. SYSTEM OP?S NORMAL