If your vehicle is showing vehicle sits unevenly from left to right on flat ground, here are the most likely causes and the parts you'll need to fix each one.
A significantly underinflated tire, or having a tire of a different size on one side of the vehicle, will cause that corner to sit noticeably lower.
The springs support the entire weight of the vehicle. Over time, a coil or leaf spring can fatigue, sag, or snap, causing the vehicle to lean to that side.
On vehicles equipped with air suspension, a leak in one of the air bags, a stuck solenoid, or a faulty ride height sensor will cause one side to drop while parked.
If suspension work was recently performed, a coil spring may not be seated correctly in its perch, or the rubber spring seat/insulator was left out during reassembly.
Hitting a large pothole, curb, or debris can bend a control arm or strut assembly, permanently altering the geometry and ride height on that side.