Same here on MP640. Error went away after washing printhead. A week of no use it came back. Washed again and fixed. Another week of no use the error returned to stay.
Same here on MP640. I managed to get it working again by cleaning printhead with water and contact points with vinegar. I got some perfect 5x7 glossy prints. Didn't use printer for 1 week and then U052 error came back after start up. I cleaned prin...