One problem related to alternator/generator/regulator has been reported for the 2006 Volvo S40. The most recently reported issues are listed below.
At least 5 times I have had the car in the Volvo dealership. The car without warning, powers down to 50%, the windshield wipers start up, all the gauges drop to zero position and abs brake malfunction lights light up. If you pull over and stop, the car shuts down and you can not pull out the key. If I wait 15 minutes, the key can be turned off and you can restart the car. While the check engine light stays on, everything else is normal till the next time. It had done this 6 times in the last 6 months. Dealer can not figure it out other them a electrical malfunction from somewhere in the computer. If it happens going up a grade or hill, the power down slows the car in which is is sometimes impossible to power up over the hill. Every time we take it to the dealer, it then runs with no problem, but lasts 2 or 3 weeks before acting up again. They have changed the batter, alternator, unplugged and replugged the computer terminal. This car is unsafe and unreliable to take on long trips. Do you know of a recall to get this problem fixed ?.