Been getting these two codes on and off. Only found one thread on here mentioning only one of them. Has anyone seen these? BMW 2C57 and 2C91.

 

I have this code 2C91 as well and I have asked that question here but no one has answered it yet. Still investigating it.

 

2C57 is 'low boost pressure' likely due to a leak somewhere (valve cover / diverter valve diaphragm / failed wastegate etc)

2C91 is likely due to the blow off valve sticking open.

I would suggest that the same issue is causing both of these codes....and there is one common item to both.

 

Is the blow off valve on the turbo? Is that particular part replaceable or do I need to replace the whole turbo unit? Do you have pictures so I know where it is and what it looks like?

Many thanks

 

If you take the intake tube off of turbo you will see the Diverter valve. It takes a 5mm hex or t27 to take the three bolts off.

This is what mine looked like, but I didn’t see any codes.

Old style on left, new style on right. ECS has the pierburg’s for under 40. That is what is on the right.

 

Thank you very much Jason

 

I had the same problem......and was starting to suspect the wastegate.......because that is the error in the OBD......but I found out that my indy mechanic (after doing a bunch of repairs) had left a hose disconnected. The moment I re-connected this hose.......the wastegate related went away. See photo below for the hose and the barb connector I am talking about: