On January 1st 2004, a GPS clock failure occurred suddenly onboard the GPS satellite PRN23 at around 18:30 UTC with the signal being transmitted for hours after that. The Unhealthy flag of its navigation message, used by the receivers to discard its measurements from the navigation position computation, was raised a few hours after the occurrence of this event. It was observed that the estimated user position was impacted in different manners depending on the different technology/firmware embedded in the receivers, and on the integrity monitoring information available to the receiver. Indeed, depending on the technology/ firmware used to track the signals and produce the raw measurements from the received GPS signal, the measurements and thus the position is affected differently. The integrity monitoring mechanism, depending on whether the receiver is GPS only, RAIM or SBAS for example also has an influence. For SBAS receivers, the reaction with WAAS and ESTB (the EGNOS demonstrator) was analyzed. The behavior of GPS only and RAIM receivers was also studied thanks to real data and was replayed using a signal generation tool. Following our investigation of these different observations, and using the information given on the onboard failure, this type of event was characterized and a simulation scenario using a GPS signal generator has been defined. This scenario will be used to reproduce both satellite effect and receiver behavior in order to test the reaction of other different receiver technology in front of the same event. The resulting behaviors of the receivers are in line with the actual observations made by three receivers on Jan 1st, and the failure has been tested successfully using a Septentrio receiver. So this simulation can be used as a benchmark for receiver validation or prediction of its behavior. This paper starts with the presentation of the actual observations made with GPS only, SBAS and RAIM receivers. Then, we show results of the investigation carried out to understand the effect of the failure on different receivers and more particularly on Novatel OEM3 and OEM4. Next, we present the simulation results obtained for the same two types of receivers. Then, we present the results obtained with an other type of receivers. Following this, we discuss the work that now can be done on EGNOS system behavior. Finally, we propose a conclusion on the reuse of the simulation scenario.