AUDI A4 LIMP MODE

[wakz]

Hi i am new to this please help.

i have an audi a4 tdi b8 2012 177bhp sline which is going into limp mode (glow plug light flashing)

initially the car would go into limp mode time to time but lately becoming more often.

i took this to my local garage to put on the diagnostic and initially came up with egr valve error.

so i had my egr replaced costing meover400 pound. but still with the same issue!

now every time i start the car it straight goes into limp mode. i have had it diagnosed again and coming up with open circuit flap ?

does anyone know what this means as this is getting frustrating and the car does not have the power it should