As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, BOTH ENVIR FAIL LIGHTS CAME ON, CREW RETURNED TO STATION WITH NO FURTHER INCIDENT. LEFT SYSTEM WAS INITIALLY REPAIRED BY REPLACING PRECOOLER THRU VALVE & BYPASS VALVE. AFTER EXTENSIVE TROUBLESHOOTING, THE RIGHT SYSTEM WAS REPAIRED BY REPLACING SHORTED PRESSURE SWITCH. THIS SWITCH WAS INTERMITTENTLY & PARTIALLY INTERNALLY SHORTED BETWEEN 4 OF THE PINS TO EACH OTHER AND TO THE CASE. THIS INTERMITTENT FAULT IS SUSPECTED TO BE ROOT CAUSE OF THIS INCIDENT.