Categories	Definition/explanation of general cause	Definition/explanation of specific cause	Example
Maintenance (K)	Maintenance failure (K1) The vehicle, or parts of the equipment, is out of order due to inadequate or incorrect maintenance.	Tyres (K1.1) One or many tyres have been inadequately maintained or checked and does not perform as expected.	A tyre explodes because it has been worn out.
		Steering (K1.2) The steering system has been inadequately maintained or checked and does not perform as expected.	The level of servo oil is to low.
		Brake system (K1.3) The brake system has been inadequately maintained or checked and does not perform as expected.	The brake-blocks have not been replaced for a long time.
		Lighting (K1.4) The lighting has been inadequately maintained or checked and does not perform as expected.	A non-functioning brake light has not been replaced.
		Other (K1.5)
	Inadequate quality control (K3) The vehicle, or parts of the equipment, have not been subject to adequate quality control by the responsible party, e.g. the user.	Other (K3.1)
Vehicle design (O)	Unpredictable system functions/characteristics (O1) The characteristics of the vehicle become unpredictable under some circumstances.	Load (O1.1) A certain amount of load makes the vehicle behave unpredictably.	If one is driving with a lot of baggage in the trunk and enters a curve with too much speed, the car might become under steered and go off the road.
		Other (O1.2)
	Inadequate HMI (O2) The interaction between user and an in-vehicle system is inadequately designed.	Other (O2.1)
	Inadequate ergonomics (O3) The driver seat, for instance, is inadequately designed from an ergonomic point of view.	Other (O3.1)

Taken from Paulson R (2005)