As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EN ROUTE, THE FLIGHT CREW NOTICED THIER WAS NO LOW PRESSURE COMPRESSOR SPEED (NL) INDICATION FOR THE LEFT ENGINE. MAINTENANCE CONTROL ADVISED THE CREW TO DIVERT TO COS WHERE REPAIRS COULD BE MADE. AIRCRAFT LANDED WITHOUT FURTHER INCIDENT AT COS. COS MX REPLACED THE LEFT ENGINE NL PROBE IAW AMM77- 14-01. ENGINE GROUND RUNS WERE SATISFACTORY.