One problem related to battery has been reported for the 2004 Volvo S40. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Volvo S40 based on all problems reported for the 2004 S40.
2004 Volvo S40 experiencing problems with the rear tail light assembly. The left rear tail light assembly was intermittent. At night there would be no rear tail lights. The right front park light and the yellow side marker light had gone out as well. The dealer replaced the cem. The vehicle's battery lasted 8 months.