I see lots of posts about failed HPFPs in R56s. Particularly alarming to me is that it seems it can fail without warning, causing the car to die suddenly or go into limp mode. Looking at this from a proactive standpoint, is there anything that can be done to check the condition of the HPFP prior to a "sudden" failure? Fuel rail pressure is a PID accessible with any generic OBD scan tool; would certain pressure ranges designate a healthy vs dying HPFP? Any other early failure warning symptoms?

 

I don't think there are any warning signs until it actually fails. One thing you can do to prevent failure, is to stay away from fuel with ethanol in it. I'm still on my original pump, but I've only used fuel with ethanol 2 times since I've owned the car. And that is only because I was in an are where there was nothing else.

 

I discovered mine was about to fail when I turned off the auto AC one first nice day and the car stumbled all over the place at idle. With the AC on, the idle level was boosted enough to mask the issue.