Opener displays E15; door may move but courtesy light or accessories behave erratically; sometimes follows wiring of external key switch or keypad.

Safety first: Disconnect power before altering accessory wiring.

• Step 1 – Identify recent changes: If E15 appeared after adding an accessory (key switch, keypad, home automation interface), disconnect that device and test the opener.
• Step 2 – Inspect accessory wiring: Verify that external switches are wired to the correct B&D terminals and are using dry contacts only (no external voltage).
• Step 3 – Test for stuck switch: Disconnect the accessory wires at the opener and use a multimeter to check that the external switch is open when not pressed.
• Step 4 – Remove incompatible devices: If a third‑party device is injecting voltage or drawing excessive current from the terminals, remove it and consult B&D for approved interfaces.
• Step 5 – Clear error: After correcting wiring, power cycle the opener and confirm that E15 is cleared and normal operation is restored.