Had a prob with my Marea Weekend JTD that the dealer (Huttons in Weston-super-Mare) initially failed to fix. Diag had shown an overboost valve problem and valve was replaced to no avail. Their Tech said he'd surf the forum that evening for ideas, so I looked it up myself and beat him to it (split in underside of air hose causing over-rich fuel, black smoke and intermittent injector/engine management warning light). Just shows the dealers' techs find the site useful too.