It is understood Mr Griffith’s resignation was made to reduce his travel commitments.
As chairman of Northern Iron, frequent travel to the company’s projects in Norway was required.
A spokesperson for Automotive Holdings Group said the decision will not affect Mr Griffith’s role as chairman at the car dealer network.
Mr Griffiths is also deputy chairman of Thinksmart and a board member of the Perth International Arts Festival.
“We are glad that we will be able to continue to access his very significant experience in the future,” Mr Sanderson said.
“We wish David a continued full and speedy recovery and all the best for the future.”