De or het diagnosecode?

The correct Dutch article is:

de diagnosecode

Rule Words ending in -ode: always de. See the rule

How to use diagnosecode

the diagnosecodede diagnosecode
this diagnosecodedeze diagnosecode
that diagnosecodedie diagnosecode
our diagnosecodeonze diagnosecode
your diagnosecodejouw diagnosecode
every diagnosecodeelke diagnosecode
which diagnosecode?welke diagnosecode?
a big diagnosecode / the big diagnosecodeeen grote diagnosecode, de grote diagnosecode