$1700 is excessive for TPMS and a flash.. What else did they find that would cost $1000 to fix (400 for sensors, 100 reflash and 2 hours of labor rough estimates)?
I would threaten to bring attorney into this. There is a law that protects consumers from this type of BS. Your warranty is only voided if they can prove that aftermarket modification caused a component failure. Very important, so expect to pay for new sensors, labor, not sure why reflash is needed?? But give them hell, sounds like a bunch of BS there...
2014 F32 435i xDrive AW/CR Technology/Premium/Adaptive/Winter/Driver Assistance/LEDs
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2007 X3 122k miles RETIRED! 2006 e90 330i 132k miles RETIRED!