DIAGNOSIS A small piece of torn paper or a sticky sensor flag is triggering the error. The primary sensor is in the rear paper path.
FIX Unplug the printer. Open the rear cover (the flap on the back). Use a bright flashlight. Look for a small, loose piece of paper or a sticky label. Check the two small, black plastic lever arms inside the path—these are the paper sensors. Gently move them with your finger to ensure they spring back. Use canned air to blow out the entire path. Close the rear cover and plug in.
IF THAT DIDN'T WORK The paper feed roller assembly sensor (PE sensor) is faulty. This requires disassembly to access. It's not a user-serviceable part on this model.
HEADS UP Never use lubricant on the sensor levers. It attracts more dust and will cause worse jams. Only use dry or air cleaning.