Marcin Dlugolecki, 33, from Poplar Avenue, Tividale, died at HMP Nottingham, the prison service has confirmed.
Mr Dlugolecki had denied arson at Birmingham Magistrates' Court and was due at crown court on 15 February.
An independent investigation by the Prisons and Probation Ombudsman will be carried out.
Mr Dlugolecki was found dead on 1 February.
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The fire took place in Small Heath on 16 January leaving some cars burnt out.
A man charged with arson after a fire at a Birmingham Citroën dealership has been found dead in his cell.