A failing coil does not always cause an SES light. If there are no symptoms or trouble codes it is not necessary to replace the coils as PM. Once there is a trouble code I would then replace all of them. Since failure is never mass suicide, I would not do the replacement based on a concern of becoming stranded somewhere. If I was making a long trip, had a modded engine, towing or something along those lines it would be a different consideration.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas