Unveiling the broad band X-ray continuum and iron line complex in Mkr 841

17 pages and 21 figuresMkr 841 is a bright Seyfert 1 galaxy known to harbor a strong soft excess and a variable K$\alpha$ iron line. It has been observed during 3 different periods by XMM for a total cumulated exposure time of $\sim$108 ks. We present in this paper a broad band spectral analysis of the complete EPIC-pn data sets. We were able to test two different models for the soft excess, a relativistically blurred photoionized reflection (\r model) and a relativistically smeared ionized absorption (\a model). The continuum is modeled by a simple cut-off power law and we also add a neutral reflection. These observations reveal the extreme and puzzling spectral and temporal behaviors of the soft excess and iron line. The 0.5-3 keV soft X-ray flux decreases by a factor 3 between 2001 and 2005 and the line shape appears to be a mixture of broad and narrow components. We succeed in describing this complex broad-band 0.5-10 keV spectral variability using either \r or \a to fit the soft excess. Both models give statistically equivalent results even including simultaneous BeppoSAX data up to 200 keV. Both models are consistent with the presence of remote reflection characterized by a constant narrow component in the data. However they differ in the presence of a broad line component present in \r but not needed in \a. This study also reveals the sporadic presence of relativistically redshifted narrow iron lines