Code
 

What is P1124 and P1126 codes?

depends on dme version, which depends on engine and model year.

1998 boxster base model

from bentley:

1124 - fuel pump output stage

signal implausible/open circuit/no signal
short to ground/below lower limit/lean mixture threshhold
short to B+/above upper limit/rich mixture threshold

(yes, all 3 are listed - don't ask me)

1126 - oxygen sensing adaptation, upper load range, cyl 1 - 3

short to ground/below lower limit/lean mixture threshhold
short to B+/above upper limit/rich mixture threshold

good luck