HP 2000CP 2500CP - Manual (Page 99)

Service Tests 4-13 HP DesignJet CP Series Printers
Only replace one component at a time and perform the test again
before replacing another component. Using this procedure you
will be able to determine exactly which component failed.
The test is continued on the next page.
Encoder Strip Failure
If there is a problem with the Encoder Strip then the following message will
appear:
D “D0304 Fail” - The Encoder Strip has failed.
In this case, Replace the encoder strip
' page 8-32.