Ask your mechanic if he had to temporarily remove the injector lines or not. This would provide some insight to those users on this board as to the possibility for a contamination inside the injector nozzle. Also - ask for more information as to which O-ring was replaced. I cannot think of any large O-ring except for maybe the one under the pre-filter but that should only take about 10 minutes to replace.

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Scott C.

2006 E320 CDI (120k miles)
FOR SALE: 1998 E300 Turbo Diesel - Black w/Tan Leather - Euro delivery (236k miles)