The Turbo Charger on the Cummings Engine has failed twice. At 9 months and 3500 miles we had to have the turbo charger replaced. Now with 20,000 miles and three years, 2 months, the check engine light came on and the diagnostics says the turbo charger needs to be replaced. Any ideas out there what could be causing this problem? It seems unlikely that we could have had two bad turbo chargers to me. Any imput would be appreciated. Thanks, Joan