As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAINT LIGHT ON AFTER LANDING. GROUNDED - YES. REMOVED ENG 2 RIGHT IGNITER PLUG REF B737-9 AMM 74-21-02-00-802. INSPECTED IGNITER PLUG AND FOUND UNIT FAILING. REPLACED RIGHT IGNITER PLUG REF AMM 74-21-02-400-802. PERFORMED TASK 71-00-00-730-805 TEST NO. 19 AND NO DEFECTS NOTED. ENG NO. 2 STARTED AND RAN ON RIGHT PLUG ONLY AND NO DEFECTS NOTED.