Why a New PW Sensor Still Triggers a Paper Jam Error: Causes, Error Codes, and Fixes

Question: I purchased a PW (paper width) sensor and had it installed, but the printer is still showing a paper jam error code. What could be causing this, and how can I fix it?

Answer:

When a printer continues to report a paper jam error code even after replacing the PW (paper width) sensor, it usually means the problem isn't limited to the sensor alone. The PW sensor's job is to detect the presence and width of paper as it enters the print path. If the printer believes paper is stuck when it isn't, something else in that detection chain may still be failing.

Here are the most common causes and what to check next:

1. Incorrect PW Sensor Installation or Alignment
Even a brand-new sensor will trigger a paper jam code if it's slightly misaligned. The sensor flag or actuator must move freely and return to its resting position. If it's bent, rubbing against plastic, or not seated correctly, the printer will think paper is constantly present.

2. Damaged or Improperly Seated Sensor Cable (FFC/FPC)
The PW sensor relies on a flat flex cable to communicate with the main board. If that cable is:

• Creased or cracked

• Inserted backward

• Not fully seated in the connector
  the signal sent to the printer can be incorrect, resulting in a persistent paper jam error.

3. Obstructions in the Paper Path
Tiny scraps of paper, adhesive labels, dried ink, or debris are notorious for causing false paper jam codes. Even if the printer looks clear, inspect:

• Under the carriage

• Near the platen roller

• Around the PW sensor flag area

A flashlight and tweezers can help reveal things that are easy to miss.

4. Dirty Encoder Strip or Timing Issues
If the encoder strip is dirty or smeared with ink, the printer may lose track of carriage movement. When the printer can't correctly synchronize paper feeding and carriage position, it may default to a paper jam error code as a safety response.

5. Main Board or Logic Misinterpretation
In some cases, the issue isn't the sensor at all but the main board misreading the signal. This can happen due to:

• Static damage during installation

• Corrosion or oxidation on connectors

• A failing logic circuit

Unfortunately, this is harder to confirm without hands-on testing.

6. Firmware State or Calibration Problems
After sensor replacement, some printers require proper power resets or internal recalibration. If the printer still "remembers" the old fault condition, it may continue throwing the same paper jam error code even though the sensor itself is new.

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems. Because of this, we're not able to provide remote troubleshooting, step-by-step repair instructions, or direct support for printer repairs. We do, however, offer an in-person evaluation and repair service through our local diagnostic facility at BCH Technologies Printer Repair Service (https://bchtechnologies.com/printer-repair-service). Due to high demand, repairs are handled on a first-come, first-served basis, and it may take a few weeks before we're able to accept a drop-off.

Our services are structured to repair either an entire printer or specific components, with clear intake instructions. That said, we're aware our rates may not be the most economical option. For that reason, we strongly encourage self-help through online research. A great place to start is YouTube, especially our BCH Technologies YouTube channel (https://youtube.com/@bchtechnologies). Use the search icon next to the "About" section on the right-hand side of the channel page to look up specific topics. I receive dozens of messages daily asking if we've made a video on a particular issue. After more than nine years of creating content, it's difficult to remember every video, so YouTube's search feature is by far the fastest way to find relevant material. YouTube may also suggest helpful videos from other creators that could guide you further.

Thank you again for reaching out and for your continued support. We truly appreciate your patience and your trust in BCH Technologies, and we wish you the best of luck getting your printer back up and running.