As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHX - AIR TURNBACK - 2/26/01 - EN ROUTE FROM PHX TO DEN WHEN THE LEFT ENGINE ANTI-ICE WAS SELECTED ON THE BLUE LIGHT REMAINED BRIGHT WITH NO INCREASE IN N2; THE AIRCRAFT RETURNED TO PHX. IN PHX MAINTENANCE TROUBLESHOT AND FOUND THE ANTI-ICE VALVE HAD FAILED IN THE CLOSED POSITION; THE LEFT ENGINE ANTI-ICE VALVE WAS REPLACED AND FUNCTIONAL CHECKS WERE GOOD.