As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
COWL VALVE OPEN WHEN OFF DISAGREEMENT WITH THE SWITCH POSITION NOTICED ON ROLLOUT. GROUNDED - YES. IAW B737-900 FIM 30-21 TASK 804 PRSOV MANUAL OVERRIDE TO OPEN POSITION COWL VALVE OPEN LIGHT EXTINGUISHED. CYCLED ENGINE ANTI-ICE VALVE, COWL VALVE OPEN LIGHT OPERATED AS REQUIRED.