Hope this helps some of you avoid an unnecessary cost. I have a 7/70 MB extended warranty on my 2012 E350 BT. I made an appointment to have a repair and was told by the dealer that I would need to pay $165 for a diagnostic fee. After that the repairs would be covered if it's a warranty item. I read my contract and it clearly states that if the repair is a warranty covered item all labor, parts, and diagnostic costs are covered free of charge.

I called MB Customer Service and they verified that fact and called the dealer for me. I talked to the dealer rep and they then agreed. The diagnostic fee would be charged ONLY if the repair was not a warranty covered repair.

Read your extended warranty contract and be prepared to argue against the diagnostic fee if you have a warranty claim.

This is fairly common knowledge in the auto industry...if a repair is covered under warranty, there is no charge for the repair or diagnostic.

If the repair is not covered, then you will pay a diag fee.

Another way to think of this:

If you suspect a broken part, you come in to have it diagnosed. There is no broken part to be found, therefore there is no warranty claim to be made. In this case, you are paying for the labor hours to discover whether or not there was a problem in the first place.

Glad you got it worked out, though!

I hear you and that's understandable. However, I was told by the Service Writer I had to pay the diagnostic fee above and beyond the warranty repairs.

Had the dilemma years ago with rust spots on headliner in ML.
The warranty would cover if the rust was due the roof defect, but dealer wanted $1200 retainer for headliner removal and investigation.
We decided we can live with the dirt.