Door will not open fully or stops mid‑travel and the Sommer display shows E4.

Safety: Disconnect power before adjusting mechanical stops or working near the door hardware.

• 1. Verify correct rail and door height: Confirm the installed Sommer rail kit matches the door height (e.g., 7 ft vs 8 ft kit). A too‑short rail can cause E4 when the opener reaches the mechanical end before the programmed limit.
• 2. Inspect for physical stops: Check for bolts, brackets, or track stops that might be preventing full travel. Remove any non‑factory obstructions.
• 3. Clear limit memory: Follow the Sommer manual to reset travel limits (often by holding the PROGRAM button until LEDs cycle, then confirming reset).
• 4. Re‑program limits: Run the door to the fully closed position and set the close limit. Then run to fully open and set the open limit, following the exact button sequence in the Sommer instructions.
• 5. Test several cycles: Operate the door 3–5 times to ensure it reaches both limits without stopping early or hitting the rail end.

If E4 returns immediately after a proper re‑program, the control board’s memory may be failing and the board should be replaced.