Epson WF-7720 Error 033506: PIS Sensor and Safe Troubleshooting
- By Ellen @BCHTechnologies
- On Oct 09, 2026
- Comment 0
Question:
What does error 033506 mean on an Epson WorkForce WF-7720? Could the error have started after refilling the cartridges, is there a button-hold reset, and should I replace the PIS sensor?
Answer:
Thank you for contacting BCH Technologies. We're sorry we could not answer sooner. Printer problems are often urgent, but we want to give every question careful thought so we can provide a detailed answer. Thank you for supporting BCH Technologies and the BCH Technologies YouTube channel [https://youtube.com/@bchtechnologies].
On the Epson WorkForce WF-7720, error 033506 is associated with excessive light detected in the photo ink sensor (PIS) system. The service information for this code points to the full ink cartridge jig or PIS sensor as possible sources; a failed sensor is not confirmed from the code alone. Refilling all cartridges shortly before the error appeared does not prove that the refill caused it.
Start with non-invasive checks: make sure the printer cover is fully closed, check for anything visibly blocking the carriage area, and restart once using the printer's normal power control. The video does not document a button-hold reset for 033506, so avoid undocumented reset combinations. Do not order or install the video's sensor until the seller confirms the exact part is compatible with the WF-7720; the video may demonstrate other models.
If the error returns, the PIS sensor, its cable or board, or the cartridge jig may need model-specific diagnosis. Stop repeated restart attempts and avoid opening the printer if it is under warranty or you are not equipped to work safely around internal electronics. Search the BCH Technologies YouTube channel [https://youtube.com/@bchtechnologies] for WF-7720 and error 033506 for related guidance. For hands-on help, contact BCH Technologies about its printer repair service [https://bchtechnologies.com/collections/printer-repair-service] and provide the exact model, full error code, and when it appears.