Software reliability is an essential design metric in emerging large-scale multiprocessor embedded systems. Designers should identify soft error susceptibility of multiple applications executing in parallel early in the design time to ensure reliable system operation. This work proposes a non-intrusive fault injection engine that enables to conduct bespoke soft error analysis, allowing to identify and understand the soft error propagation through the processing elements (PEs). The proposed fault injection campaign evaluates the impact of soft errors considering real benchmarks in an RTL model of a distributed-memory NoC-based multiprocessor. Experiments demonstrate that 19% of soft errors are propagated to other PEs, where 31.6% of them led to erroneous computation and 58.4% to a system crash. Thus, the fault analysis must consider not only its local effect on the processor and memory but also how the fault propagates to other system components.