Epson 71H Error (Home Position Seeking Error) on L805 / Procolored Conversions: Causes, Checks, and Fixes

Question

I watched your member-only content and I'm dealing with a 71H error on an Epson L805 / Procolored setup. What does this error mean, and how can I fix it?

Answer

What the 71H Error Code Means

The 71H error is a home position seeking error related to the printer's platen gap / head height mechanism, commonly referred to (on many Epson platforms) as the APG assembly (Automated Platen Gap). In simple terms, the printer is trying to move the platen-gap mechanism to its "home" (starting) position, but it cannot confirm movement or cannot detect the correct home position.

On converted machines (including some Procolored-branded Epson-based units), this can happen more often because the printer may have been opened, modified, reassembled, or operated in environments where ink mist, dust, or film debris can build up.

The Most Common Causes of 71H (and Why They Trigger It)

1) Foreign object obstruction (debris blocking the APG mechanism or sensor)

This is one of the most frequent real-world causes. Even something small-like dried ink, loose scraps of film, a cable tie tail, a screw that backed out, or paper/film dust-can prevent the platen gap mechanism from completing its travel. When the printer can't move freely to the expected position, it throws 71H.

What to do:

• Power the printer off properly, then unplug it.

• Open the cover and inspect the platen area and the path around the gap mechanism.

• Look for:

  • dried ink "globs"

  • film dust/lint

  • a dangling tube or cable

  • broken plastic tabs

  • anything rubbing or catching when parts move

If you can safely do so, gently move the carriage by hand (with power disconnected) and look for anything that snags. Don't force it-resistance usually means you found the problem area.

2) APG unit failure or incorrect assembly (wear, broken gears, mis-seated parts)

The APG assembly includes plastic parts and sometimes small gear-driven components. Over time, gears can wear, a lever can crack, or a spring can slip out of place. On machines that have been converted or worked on, it's also possible something was reinstalled slightly off-close enough to "fit," but not aligned enough to home correctly.

Symptoms that point here:

• You hear clicking, grinding, or repeated "trying" noises when it powers on.

• The printer starts its initialization, then stops and errors.

• The gap setting may feel inconsistent or the mechanism doesn't return smoothly.

What to do:

• Inspect for broken teeth on small gears.

• Look for levers/springs that appear shifted or not seated.

• Check that nothing is rubbing the frame.

• If the printer has recently been serviced or modified, re-check the assembly order and seating of parts around the platen gap mechanism.

3) APG sensor not functioning (misalignment, damage, or swapped installation)

The printer relies on sensor feedback to confirm the APG mechanism is at home. If the APG sensor is dirty, misaligned, damaged, or incorrectly installed, the mechanism might actually be moving-but the printer can't "see" it reach home, so it reports 71H.

Common reasons this happens:

• Sensor is blocked by dust/ink mist.

• Sensor flag/actuator tab is bent or not passing through the sensor correctly.

• Sensor connector was disturbed during a conversion or repair.

What to do:

• Locate the sensor and its flag/actuator.

• Carefully clean dust/ink residue (gentle cleaning only-avoid soaking electronics).

• Confirm the flag passes cleanly through the sensor gap.

• Confirm the sensor is mounted straight and not twisted.

4) Wire suspension / loose cable connection (APG cable not seated, pinched, or damaged)

Loose or intermittent connections are especially common on printers that have been opened for conversion. A cable can look "connected" but not fully seated; or it can be pinched under a cover and intermittently disconnect when the printer vibrates or moves.

What to do:

• Inspect the cable harness going to the APG assembly and sensor.

• Reseat connectors (unplug/replug carefully).

• Look for:

  • bent pins

  • oxidized contacts

  • torn flex cables

  • pinched sections under plastic covers

If the error appears after moving the printer, after a recent repair, or after shipping, cable seating becomes a top suspect.

Step-by-Step Troubleshooting Path (Practical Order)

If you want the most efficient approach, here's the order I recommend:

1. Power off/unplug → visual inspection for debris or anything obstructing movement

2. Check for obvious mechanical issues (broken gear teeth, cracked lever, displaced spring)

3. Inspect and clean the APG sensor area (confirm the flag passes correctly)

4. Reseat all APG-related connectors and confirm no pinched/damaged wiring

5. If the mechanism appears intact but still won't home, the APG unit or sensor may need replacement (depending on the exact platform and parts availability)

Addressing printer issues can get complicated because so much of it is hands-on-tiny mechanical tolerances, sensor alignment, and part condition can only be confirmed by direct inspection. Because of that, we're not able to provide remote troubleshooting, suggestions, or support for printer repairs. We do offer an in-person evaluation and repair service through our local diagnostic facility: printer repair service (https://bchtechnologies.com/printer-repair-service). Due to high demand, we run on a first-come, first-served basis, and it may take a few weeks before we can schedule your printer drop-off. Our service options are designed to repair either the full printer or specific parts, with clear instructions on how to proceed. That said, we understand our rates may not be the most economical, so we strongly encourage self-help through online research. A great place to start is YouTube-especially our channel homepage here: BCH Technologies on YouTube (https://youtube.com/@bchtechnologies). Use the search icon next to "About" on the right side of the menu bar to find videos on your exact topic. I get dozens of questions every day asking if we have a video for a specific issue, and after nine years of publishing it's hard to remember every single one-so YouTube search is the fastest method. It can also recommend helpful videos from other creators that match your exact symptoms.

Thanks again for reaching out and for supporting what we do. If you keep digging into the 71H (APG home position seeking error) with the checks above, you'll usually find it comes down to obstruction, misalignment, a failing APG mechanism, or a wiring/connector issue.