  Multiwavelength studies of radio relics at merger shocks set powerful
constraints on the relics origin and formation mechanism. However, for X-ray
observations, a main difficulty is represented by the low X-ray surface
brightness far out in the cluster outskirts, where relics are typically found.
Here, we present XMM-Newton results from a 130-ks observation of CIZA
J2242.8+5301, a cluster at z=0.19 that hosts a double radio relic. We focus on
the well-defined northern relic. There is a difference of ~55% between the
temperature we measure behind the relic, and the temperature measured with
Suzaku. We analyse the reasons for this large discrepancy, and discuss the
possibility of reliably measuring the temperature beyond the northern relic.
