What happened
On August 22, 2020, a Boeing 737-800, registration SP-ENL, was taxiing for takeoff at Warsaw Chopin Airport (EPWA) when the crew observed a "MASTER CAUTION FUEL" signal and a "FUEL FILTER BYPASS" alert pertaining to engine number 1.
Upon detecting these indications, the crew halted the aircraft on the taxiway and notified Air Traffic Control (TWR), requesting permission to return to the parking stand. While awaiting instructions, the crew attempted to perform the Non-Normal Checklist (NNC) for the fuel filter bypass. However, the crew found the procedures in the NNC to be inapplicable to the current situation, as the checklist instructions were designed for in-flight events rather than ground operations.
During the wait, the fuel filter bypass alert intermittently cleared and re-engaged after approximately 33 seconds. After receiving clearance from TWR, the aircraft taxied back to the stand. During this return taxi, the alert cleared once more. Upon arrival at the parking position, the aircraft was handed over to the operator's maintenance personnel for inspection.