What was found
ENG 1 FILTER BYPASS WARNING LIGHT ILLUMINATED AFTER TAKEOFF. FOLLOWED QRH, ENGINE NR 1 OPERATES NORMALLY. GROUNDED - YES. BEGAN PERFORMING B737-900 FIM 73-05 TASK 801. NO MAINTENANCE MESSAGES FOUND IN RECENT FAULTS OR FAULT HISTORY. AT STEP E (2) (A), FOUND NR 1 ENGINE FILTER BYPASS IN "CLOGGED CONDITION. CONTINUED WITH FIM TASK 73-05 TASK 801 AT STEP E (2) (B). R & R FUEL FILTER DIFFERENTIAL PRESSURE SWITCH, REF B737-800 AMM 73-34-01 AND INSTALLATION TEST GOOD. PERFORMED IDLE POWER LEAK CHECK & EEC TEST, IAW POWER PLANT TEST REF TABLE REF AMM 71-00-00-800-811-F00. ALL OPS TESTS GOOD & ALL INDICATIONS GOOD. AIRCRAFT OK FOR SERVICE.