Part of the generic B2A21 overview — this page covers the Ford meaning specifically.
OBD-II Diagnostic Trouble Code
B2A21
One Or More Configuration Files Missing Or Corrupt
B
Body
comfort / safety
comfort / safety
2
Generic
SAE standard
SAE standard
A
Body subsystem
21
One Or More Configuration Files Missing Or Corrupt
Severity · general guide
Varies
Body/safety — depends on system
Code type
Ford
System
Body
Model
F-150
Years
2011