P0741 Torque Converter Clutch Circuit Fault on 1999 Cadillac Deville - Diagnosis and Repair Cost

I'm experiencing a P0741 diagnostic trouble code on my 1999 Cadillac DeVille, which indicates a 'Torque Converter Clutch Circuit Performance or Stuck Off' issue. The service engine light turned off temporarily but reappeared after driving approximately 100 miles on the highway. I've also reviewed an article titled 'Diagnosing GM Converter Lock-Up Problems' for reference: http://autorepair.about.com/cs/troubles/...61701a.htm. Can anyone confirm how serious this fault is and what the typical repair cost might be? Thanks for any insights or advice.