L1800 DTF Printer Carriage Slamming Left With Flashing Red Lights - Causes and Fixes

Question:

After replacing the carriage assembly on an L1800-based DTF printer, the carriage moves extremely fast at startup, slams all the way to the left, and gets stuck. At the same time, both the ink and paper lights flash red. What steps can be taken to fix this issue?

Answer:

To address your issue: when the carriage accelerates wildly, slams left, and both the paper and ink lights flash red simultaneously, the printer is triggering a carriage position failure. This behavior is typical when the printer loses track of the carriage's position because it cannot read the CR Encoder System, which includes the timing strip and the CR encoder sensor.

Below are the most common causes and fixes:

1. CR Encoder Sensor Not Reading the Timing Strip

The clear encoder strip is what tells the printhead carriage where it is along the rail. If the sensor cannot read it, the printer reacts by slamming the carriage to one end.

What to check:

• Make sure the strip is not twisted, folded, or stretched.
  Even a slight twist can prevent the CR sensor from interpreting the markings.

• Ensure the strip is fully inserted into the small U-shaped slot of the encoder sensor on the carriage.

• Clean the strip gently with a lint-free cloth.
  Ink mist, grease, or fingerprint oil can cause the sensor to misread the strip.

• Confirm both ends of the strip are mounted securely in their metal anchors.

If the strip is misaligned by even 1-2 mm, the carriage will lose position and slam.

2. CR Encoder Sensor Cable (CRPW Cable) Not Seated Properly

If the strip is fine, the next most common problem is the CRPW ribbon cable not being fully inserted.

This cable connects the carriage sensor to the mainboard.

What to inspect:

• Check that the CRPW cable is properly inserted on both sides:

  • Into the carriage board

  • Into the main motherboard

• Make sure the cable is not reversed.
  Ribbon cables with exposed contacts must align perfectly with the connector pins.

• Look for bent pins or partially latched connectors.

A loose CRPW cable will cause the sensor to behave as if the strip is missing entirely.

3. Sensor Damage or Misalignment After the Carriage Replacement

Since you recently changed the carriage, it's possible the CR sensor itself shifted when reassembling.

Solutions:

• Verify that the sensor is sitting level and straight.
  If it's tilted, it cannot read the strip consistently.

• Make sure no screws are missing-loose mounting will cause the sensor to vibrate.

• Inspect the sensor for physical damage (cracks, bent housing, broken eye).

4. Firmware Error Triggered by Improper Position Detection

When both the paper and ink lights flash red, the L1800 typically indicates a carriage position error or CR encoder error-noted internally as an E-01 style fault on Epson engines.

While the printer doesn't show error numbers on its own, this behavior corresponds to:

• Carriage Home Position Failure

• Carriage Drive Error

• CR Encoder Failure

Fixing the physical encoder issues nearly always resolves the flashing lights.

Addressing printer issues-especially mechanical alignment and sensor-related faults-requires hands-on inspection and careful adjustments. Because of the physical nature of these repairs, we're unable to offer remote troubleshooting or step-by-step repairs. If you prefer a full diagnostic, we offer an in-person evaluation service through our local repair facility at BCH Technologies Printer Repair Service (https://bchtechnologies.com/printer-repair-service). Demand is high, so repairs are performed on a first-come-first-served basis and may involve a waiting period. Our services include complete printer repair or targeted part repairs, with straightforward drop-off instructions. That said, many users choose to self-diagnose issues through online resources-we recommend exploring printer repair videos on YouTube or visiting our channel homepage BCH Technologies (https://youtube.com/@bchtechnologies). Use the search icon next to "About" to locate specific topics. With nearly a decade of published videos, using YouTube's search is often the fastest way to find the exact guidance you need.

Thank you again for your question and for supporting our work. Your engagement means a lot to us, and we're always here to help provide clarity whenever possible.