Motivated by applications in the automotive domain, particularly the Autosar basic software standard, we present a technique to improve model-based testing by allowing model-level fault injections. These models are plugged into a larger system as executable components to test it for general tolerance to slightly varying, possibly faulty components or library implementations. Such model execution is possible through applying an automated mocking mechanism and model cross-referencing. Systematic modelling and testing is possible by having comprehensive fault models which both simulate faults and guide the model-based testing procedure towards quicker discovery of these faults. We show the principles of our method on an illustrative example and discuss how it is implemented in a commercial model-based testing tool QuickCheck and applied to a more realistic case study. More generally, this work explores multi-purpose (or meta) modelling – an approach where one parametric model is used for different test targets, like functional testing or safety testing.