On the 2002–2014 Volvo XC90 (first generation), the pressure line at the steering rack is one of the more frustrating hydraulic line replacements because the fitting is tucked above the subframe with very little wrench clearance.
Here are the steps that usually make the job much easier:
Raise the front of the vehicle securely and remove the front splash shield/undertray.
Drain as much power steering fluid as possible by disconnecting the return hose at the reservoir and catching the fluid in a drain pan.
Remove anything blocking access, depending on the engine. On many models, loosening or removing the air intake duct, engine torque mount, or heat shield improves access.
Use a crowfoot flare-nut wrench (or a line wrench if you can fit one) on the hydraulic fitting. An open-end wrench can easily round the fitting.
Turn the steering wheel (with the engine off) to reposition the rack. This can sometimes provide a little more clearance around the fitting.
If you're working at the steering rack connection, lower the rear of the subframe slightly by supporting it with a jack and loosening the rear subframe bolts a few turns. This often creates enough room to swing the wrench. Do not completely remove the subframe unless you're prepared to realign it afterward.
If the fitting is seized, apply penetrating oil and let it soak. Gentle heat on the rack fitting (avoiding rubber components) can also help.
A few additional tips:
Use flare-nut (line) wrenches, not standard open-end wrenches.
If you only have a few degrees of movement, patience is key—you may only get 1/12 of a turn at a time.
Be prepared to replace the O-rings or sealing washers supplied with the new line and refill the system with the correct Volvo-approved power steering fluid. Bleed the system afterward by turning the steering wheel lock-to-lock several times with the front wheels off the ground before starting the engine.
Could you tell me:
Which engine you have (2.5T, 3.2, V8, T6, etc.)?
Is the leaking line the high-pressure line from the pump to the rack, or the return hose?
That will let me point you to the exact fitting and the easiest access method for your specific XC90.