As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: NO EMERGENCY DECLARED DUE TO: WHEN GEAR WAS RETRACTED OUT OF LAS THE NOSE GEAR DID NOT RETRACT. GEAR EXTENDED DURING LANDING; AIRCRAFT LANDED SAFELY AT ORD. TROUBLESHOT, PER FIM 32-61-00-810-803. CONFIRMED SENSOR S853 FAULTY. REMOVED AND REPLACED S853 SENSOR, OPERTIONAL CHECK GOOD. PER AMM 32-61-51.