how to replace a fuel relay & wish one of the three behind the batery
The fuel pump relay is located behind the battery beneath the plastic cover. It is the one in the forward location and depending on your car's production year will either be a 9 or 10 pin version.
The relay just lifts off but a little side to side wiggle should help while pulling it up.
Search Mercedes-Benz 300-Class Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Mercedes-Benz 300-Class Experts