So far I have found this article:
http://www.theregister.co.uk/2013/08/08/hp_plug_password_leaking_printer_vuln/
No mention of your printer model there.
The official response from HP was posted here:
I have also discovered this site which can test for Heartbleed vulnerability:
https://filippo.io/Heartbleed/
Seems pretty straight forward. The heartbleed vulnerability can only be exploited when users have remote access to the printer. That means that printers without direct internet access should be somewhat safe behind your firewall. Attackers would need to get through that and gain access to your network before they would be able to retrieve any info from the printer itself.