One problem related to engine has been reported for the 2004 Volvo XC90. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Volvo XC90 based on all problems reported for the 2004 XC90.
Transmission failure on our 2004 Volvo xc-90 t6 awd at approximately 56,000k miles. Fortunately it was a warranty repair; however my research on automotive discussion boards like edumds indicates a very large pattern of failure of the transmission on this model.