Hilux air suspension problem

Sounds like a classic suspension failure. Could be a faulty bellows valve. Have you noticed any hissing sounds, like air escaping? That mileage of 108073 km is getting up there for the original suspension components.

No hissing that I can hear, but then again, the diesel is quite loud. What does the bellows valve actually do, and how would I check it?

Think of the bellows valve as a tiny gatekeeper for the air in your suspension. If it's defective, it will cause an air leak, preventing the suspension from inflating properly. You'll probably need to take it to a workshop to confirm that it's the air bag valve that's defective.

Indeed, it was the suspension air bag valve. Got it repaired for 590€. Appreciate the help!