The surface detector array of the Pierre Auger Observatory consists of 1660 water-Cherenkov detectors (WCDs) which sample the charged particles and photons of air showers initiated by cosmic rays of very high energy. With the AugerPrime upgrade, the collaboration aims to increase the particle identification capability of the surface detectors. Scintillator surface detectors (SSDs) will be added above the water-Cherenkov detectors and the stations will be equipped with new electronics having better timing accuracy, higher sampling frequency, and increased processing capability. Furthermore, small photomultipliers will be added to the WCDs to allow for an increase of the dynamic range of the signal readout. In October 2016, an engineering array consisting of 12 AugerPrime detector stations was installed within the existing array of the Observatory.
In this contribution, we will discuss the first results from the AugerPrime engineering array. In particular, the detector calibration in units of vertical equivalent muon (VEM) for WCD and minimum ionizing particle (MIP) for SSD. Furthermore, we will discuss the temperature dependence of the detector parameters, show the lateral distribution function of showers measured with both detector types, and present the preliminary results of the study on signals from doublet stations.