Trans fail safe will run only in 4th gear. Definitely not something you want to do repeatedly. Which engine? Must be 3.0 off disa valve. I rebuilt both mine and wife's and didn't have new gasket so I used oatey fasttape Teflon tape and it worked wonders definitely seal that disa tight

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)