Hi. New to the forum I hope someone can help. W204 C class went into limp mode... Dpf problem.... Replaced Dpf with original part at an indie.... Then started showing a fault with cylinder 1 but the mechanic said it shouldn't be a problem to drive. Skip forward a few months, EML on again... Dpf 400% full and regeneration can't be forced... Took it to dpfcleaned.co.uk today, had it removed/cleaned/refit and drove back fine... Get to my house and park... Get a LOUD knocking when put in reverse gear. No issues in any other gear. NEVER had any issues other than Dpf/cylinder 1 prior to this. The problem sounds similar to this . Could this be something to do with the Dpf not being reconnected properly or is this just an unlucky coincidence?