Epson R1390 Error Code 0xFB (PF Motor Drive Error) After Pump Replacement - Causes and Fixes

Question:
After replacing the circulation pump on an Epson R1390 (F13), the printer now shows error code 0xFB: PF Motor Drive Error. All cables appear to be properly connected, and common troubleshooting steps found online haven't resolved the issue. What could be causing this problem?

Answer:
Understanding Error Code 0xFB (PF Motor Drive Error)

The 0xFB error on Epson printers like the R1390 is typically classified as a Paper Feed (PF) acceleration lock error. This means the printer detects that the PF motor is not moving as expected-either it's stuck, overloaded, or not receiving proper feedback from the encoder system.

This error is not always caused by the motor itself. In fact, it often relates to mechanical interference or encoder-related issues, especially after recent repairs like your pump replacement.

Most Likely Causes (Based on Your Scenario)

Since the error appeared after replacing the circulation pump, the issue is very likely related to something disturbed during that process. Here are the most common causes:

1. PF Encoder Disc Misalignment or Dislodgement

• The PF encoder disc is a thin, circular plastic disc attached to the PF motor shaft.

• It works with a sensor to track rotation and speed.

• During pump replacement, it's easy to accidentally bump or loosen this disc.

• If the disc is:

  • Misaligned

  • Dirty (ink/smudges)

  • Cracked

  • Not spinning freely

  → The printer cannot read movement properly and throws 0xFB.

✅ What to check:

• Inspect the PF encoder disc carefully.

• Make sure it is firmly seated and not wobbling.

• Clean it gently with a lint-free cloth if dirty.

2. PF Encoder Sensor Issues

• The sensor reads the encoder disc.

• If it's:

  • Blocked by ink or debris

  • Slightly misaligned

  • Disconnected

  → It will fail to detect movement, triggering the error.

✅ What to check:

• Ensure the sensor is aligned with the disc.

• Clean the sensor area (no force).

• Verify the cable connection to the mainboard.

3. Cable or FFC (Flat Flexible Cable) Disconnection

Even if cables look "plugged in," they may not be:

• Fully seated

• Inserted straight

• Locked properly

During pump replacement, cables around the PF assembly can shift.

✅ What to check:

• Re-seat all related cables:

  • PF motor cable

  • Encoder sensor cable

• Look for bent pins or loose connectors.

4. PF Motor Failure or Binding

While less likely (since it worked before), it's still possible:

• The motor was stressed during handling

• Something is physically blocking the paper feed mechanism

✅ What to check:

• Try gently rotating the PF gear manually (with power off).

• Ensure there's no resistance or grinding.

• Look for:

  • Foreign objects

  • Misaligned gears

  • Ink tube interference from the new pump install

5. PF Mechanism Overload (Very Common After Repairs)

After installing a new pump, tubing or components may:

• Press against moving parts

• Restrict gear movement

• Create drag in the system

This leads to the motor failing to accelerate properly → 0xFB error.

✅ What to check:

• Verify that all tubes and wires are routed correctly.

• Ensure nothing is interfering with the PF gear train.

Key Insight

Based on your description, the most probable cause is:

👉 The PF encoder disc was accidentally knocked loose or misaligned during the pump replacement, or the encoder sensor is not reading correctly.

This is extremely common in repairs involving internal components.

Important Note on Troubleshooting

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems. Therefore, we're not able to provide remote troubleshooting, suggestions, or support for printer repairs. We do offer an in-person evaluation and repair service via our local diagnostic facility (Printer Repair Service: https://bchtechnologies.com/printer-repair-service). Given the high demand, we operate on a first-come, first-served basis, and it may take a few weeks before we can accept your printer for drop-off. Our services are structured to repair either the entire printer or specific components, with clear guidance on how to proceed.

We also understand that our repair rates may not be the most economical option. For that reason, we strongly encourage self-guided research. A great place to start is YouTube, including our channel homepage (https://youtube.com/@bchtechnologies). Use the search icon next to the "About" section on the right-hand side of the menu bar to find videos related to your issue. With hundreds of videos created over the past nine years, this is the fastest way to locate relevant content. Additionally, YouTube may recommend helpful videos from other creators as well.

Thank you again for reaching out and for your continued support. We truly appreciate you being part of our community.