As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING INITIAL LEVEL OFF AT FL340 "#1 FILTER BYPASS" ILLUMINATED. RAN QRH PROCEDURE. QRH ALLOWED TO CONTINUE AS #1 ENG SHOWED NORMAL INDICATIONS. GROUNDED - YES. CONFIRMED PART # AND EFFECTIVTY REMOVE AND REPLACE #1 ENG FUEL FILTER DIFFERENTIAL PRESS SWITCH PER B737-800 AMM 73-34-01 ACCOMPLISHED EEC BITE TEST PER AMM 73-21-00 AND ENG IDLE POWER LEAK CHECK PER AMM 71-00-00 NO DEFECTS NOTED. PULL AND RESET 2 C/B'S.