FD 300 Paper Error Won’t Go Away? Troubleshooting Guide (Q&A)

If your Formax FD 300 folder is throwing a paper error that won’t clear — even after you’ve removed the paper and restarted the machine — you’re not alone. This is one of the most common service calls we get at All For Mailers. Below is a quick Q&A troubleshooting guide based on a real support case, to help you get your FD 300 back up and running fast.

Q: The paper error on my FD 300 won’t go away. What should I check first?

A: Start with the basics. Turn off the power and check the fold plates to see if paper is jammed. If it is, remove the fold plate(s), clear the jammed paper, re-install the fold plate(s), and then power the machine back on.

If the paper error still won’t clear, walk through these additional checks that often cause the same symptom:

1. Open both fold plates and inspect the paper path. Even a small scrap, a torn corner, or a dog-eared sheet in the path will keep the error active because the sensor still “sees” paper. Blow out any paper dust while you’re in there.
2. Clean the sensors. The FD 300 relies on optical sensors in the paper path. Paper dust, toner residue, or a piece of stuck paper over the sensor eye will make the machine think paper is present (or stuck) even when the path is clear. Use a can of compressed air and a soft lint-free cloth.
3. Check the infeed tray. Make sure paper is loaded correctly with the leading edge under the feed tires, and that the side guides are snug but not pinching.
4. Power cycle the machine. Turn the FD 300 off for about 30 seconds, then back on to reset the control board after clearing the jam.
5. Confirm the fold plates are fully seated on their alignment pins (upper plate on top, lower on bottom). A plate that isn’t seated all the way can trigger errors.

Q: Is the FD 300 paper error coming from the feed-in sensor or the exit sensor?

A: It could be either. The FD 300 has a feed-in (infeed/registration) sensor and an exit/paper-out sensor in the fold path, and a “PAPER ERR” can be triggered by either one — typically because:

• The feed-in sensor is blocked or dirty, or the paper isn’t reaching it properly (worn feed tire, paper not under the tires, guides too tight).
• The exit/paper-out sensor still sees paper (jam fragment in the fold plates) or is dirty/failed, so the machine thinks a sheet never cleared.

Q: How do I tell which sensor is triggering the error?

A: The FD 300 operator’s manual doesn’t tell you which sensor is triggering — it just says check the fold plates for a jam. Practically, the fastest diagnostic is to clear the path, clean both sensors with compressed air, and power cycle the machine.

• If the error returns immediately on power-up with no paper in the machine, a sensor is likely dirty or failed — most commonly the exit sensor in the fold plate area, since that’s where debris accumulates.
• If it only errors during a run, it’s usually a feed issue at the infeed sensor or worn feed tires.

Q: What if cleaning and clearing the jam don’t fix the FD 300 paper error?

A: If cleaning and clearing don’t resolve the error, the next step is replacing the suspect sensor. The FD 300 manual doesn’t include a sensor-level diagnostic procedure, so we recommend ordering the replacement sensor from SuppliesForMailers.com or contacting our support team for help identifying the correct part.

FD 300 Replacement Sensor Part Numbers

• 03-B0050 — Paper Feed-In Sensor: Order here
• 03-B0020 — PCB Emitter (item 6): Order here
• 03-B0030 — PCB Receiver (item 2): Order here

Still stuck? We’re here to help.

If you’ve tried the steps above and your FD 300 paper error still won’t go away, give us a call at 866-430-2874 or visit SuppliesForMailers.com to order parts and sensors. Our team at All For Mailers has decades of experience supporting Formax folders and mailing equipment, and we’re happy to help you diagnose the issue and get back to production.