1. A diagnosis engine ( 100 ) for estimating a status of an entity ( 150 , 200 ) with a plurality of components (c 1 ,. .. , c n ) which each is assumed to be in a fault-free mode or be in exactly one of at least one fault mode, the diagnosis engine ( 100 ) comprising: a processing unit ( 110 ) adapted to analyze test results (P 1 , P R ); and at least one storage area ( 120 , 130 , 140 ) adapted to store diagnostic data in respect of the entity ( 150 , 200 ), wherein said processing unit ( 110 ) is adapted to: receive an original disjunction of diagnostic expressions (D) indicating at least one of said modes for at least one of said components (c 1 ,. .. , c n ), receive test results (P) of a set of diagnostic tests (T) in respect of the entity ( 150 , 200 ), the result of each test (t 1 ,. .. , t x ) being a disjunction of statements (P 1 1. .. P 1 x ;. .. ; P R 1. .. P R z ) wherein each statement (P J j ) indicates at least one of said modes for one of said components (c 1 ,. .. , c n ), store the expressions in the original disjunction of diagnostic expressions (D) to a temporary disjunction of diagnostic expressions (D old ) in a first storage area ( 120 ), investigate, for each diagnostic expression in the temporary disjunction of diagnostic expressions (D old ), whether or not a currently investigated diagnostic expression (D 1 ) implies the test result (P J ); if not so, remove the expression (D 1 ) from the temporary disjunction of diagnostic expressions (D old ); and, for each statement (P J j ) in the test result, generate a joint diagnostic expression (D new ) representing a conjunction of the statement (P J j ) and the currently investigated diagnostic expression (D 1 ), compare the joint diagnostic expression (D new ) with each diagnostic expression in the original disjunction of diagnostic expressions (D) except for the currently investigated diagnostic expression (D 1 ), and if an original diagnostic expression (D k ) is found, where the joint diagnostic expression (D new ) implies the original diagnosis expression (D k ), discard the joint diagnostic expression (D new ), and otherwise, add the joint diagnostic expression (D new ) to an updated disjunction of diagnostic expressions (Q) in a second storage area ( 130 ), the updated disjunction of diagnostic expressions (Q) representing an estimated status of the entity ( 150 , 200 ), thereafter add all remaining diagnostic expressions in the temporary disjunction of diagnostic expressions (D old ) to the updated disjunction of diagnostic expressions (Q), and produce a status report (R[Q]) based on the updated disjunction of diagnostic expressions (Q).