Originally posted by docspin someone told me that on the old DSLR with previous autofocusing firmware the problem is more probably to happen ... It's true ?
Not likely. Best answer has been that the motor in the lens fails or jams after some time. So, no firmware change in the camera is going to affect that.
There is more involved than just time of production. Many people still have older ones that work fine. And some people report failure on newer ones. This may be due to parts sourced from different places, variable quality in the parts or maybe even just how a particular photographer uses the lens. No one (except possibly Pentax) really knows.
There is a thread here:
https://www.pentaxforums.com/forums/pentax-news-rumors/199282-end-sdm-autofocus-failure.html reporting that Pentax has changed the motor components or design and that they feel there should be no failures in lenses made in 2012.