Failure mode and effects analysis are performed for a dual levelling valve pneumatic suspension to determine the effect of suspension failure on tractor–semi-trailer dynamics, using a detailed model of suspension pneumatics coupled with a truck dynamic model. A key element of failure analysis in suspensions with one or two levelling valves is determining the effect on the vehicle body roll when one or more failures occur. The failure modes considered are mainly the suspension pneumatic components, including clogged levelling valve, bent control rod, disabled lever arm, and punctured or leaking connectors and pipes. The pneumatic suspension is modelled in AMESim, with critical parameters established through component testing. Upon validating the AMESim component model experimentally, the pneumatic suspension model is integrated into TruckSim for studying the consequences of suspension failure on truck dynamics. The simulation results indicate that the second levelling valve in a dual-valve arrangement brings a certain amount of failure redundancy to the system, in the sense that when one side fails, the other side can compensate for the failure. Equipping the trailer with dual levelling valves brings an additional stabilising effect to the vehicle in the event of tractor suspension failure.