First spotted on Petapixel, Leica is now acknowledging the sensor corrosion issues that has been reported as far back as 2010. The problem could potentially be present in any Leica camera models M9, M9-P, M-E and M Monochrom that contain sensors KAF-18500 covered with Schott S8612 glass.
Older M8 models or newer cameras that contains different sensors and cover glass are not affected. To check if your Leica camera sensor is affected, simply take a picture of the sky with the lens stopped down between f/11 and f/16 and if you spot anything similar to the pictures below, then it could mean your camera sensor is corroding.
Leica is now offering free sensor replacement for affected cameras regardless of age, and according to this forum post Leica will replace the CCD sensor with the same type shipped with the original cameras but doesn’t promise that corrosion won’t happen again. The good news is if it does, Leica will offer another new replacement.
Leica Customer Care Centre is located at #06-04 International Building along Orchard Rd here in Singapore.