open the rear hatch, It is located on the driver side under the deck/ next to the spare.
there is a post in the engine compartment for jumpstart or charging on the driver side.
In the trunk. Left-hand side.
The battery for the Volvo S40 2004 is under the hood on the driver's side in the front just behind the lights . It is encased in a black Styrofoam case which lifts straight up to remove.
I posted pictures on the location and replacement of an ambient temp. sensor for a 2001 S40. Google "ambient temperature sensor location/replacement" or go to Matthew's Volvo site and search there.
main battery is in the boot (trunk) on the drivers side, under a removable panel.
In the 2003 Passat Wagon (US), it is under the carpet directly in front of the driver's seat.
On Volvo S40 2004 onwards, when the remote key battery voltage is low a text message is displayed in driver's information message screen that the remote key battery voltage is low which means the remote key battery should be replaced. .ab.
alot of newer vehicles have the battery located in a remote location like under the back seat
The 2004 Volvo XC70 has 20 valves.
The 2004 Volvo S80 has 20 valves.
The 2004 Volvo XC90 has 20 valves.
The 2004 Volvo S60 has 20 valves.
The 2004 Volvo C70 has 20 valves.