As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMB OUT FMC SHOWED IRS LEFT DRIFT IRS LEFT SIDE INCREASED TO 24 WITH VERIFY POS IRS/IRS. RT IRS FUNCTIONING NORMAL. GROUNDED - YES. DIVERSION TIME 25 MINUTES - REPLACED L/H ADIRU REF B737-800 AMM 34-21-01-400-801 OPENED & CLOSED 3 C/B'S OPS CK OK REF AMM 34-21-00-710-801 OPENED & CLOSED 1 C/B ACCOMP DFCS ADIRU LRU REPLACEMENT TEST REF AMM 22-11 TASK 802 "ALL TESTS" PASS.