I have a 325i se touring. It has failed the mot due to rot in the subframe. It’s a 2005. Is this a common fault?

Hi Philip

My X5 is 17 years old and the only rust on the rear subframe is surface rust (that I am aware of) so my answer would be "no not common" but depending where it spent it's early life, say near the sea or North of the Border where there may have been a lot of road salt in the darker months. 

I would balance the cost of welding against maybe sourcing a complete subframe from a dismantler? It could be rebushed cleaned and painted then swapped over bleeding the brakes is the only tricky job.

Dave