As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON PRE FLIGHT CHK CREW REPORT HF1 SHOWED FAIL ON CONSOLE. GROUNDED - YES. PERFORMED HF1 BITE CHECK PER B737-800 FIM 23-11 TASK 801. NO FAULT NOTED. CYCLED HF1 C/B PER B737-800 AMM 20-60-05 AND OPS CHECK NORMAL ETOPS GRND VERIFIY IS SUCCESSFUL.