What was found
IAH FLIGHT 2881, DURING CLIMB, THE CREW REPORTED A LANDING GEAR AIR GROUND FAIL MESSAGE AND THAT THE LANDING GEAR WOULD NOT RETRACT. THE AIRCRAFT RETURNED TO IAH WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE ADJUSTED THE LEFT MAIN GEAR PROX SWITCH, OPERATIONALLY CHECKED WITH NO DEFECTS, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.