The Taptic Engine is what Apple uses to power the the tap-like haptics in the Apple Watch and MacBook.
According to a report, one of the two suppliers of the part for Apple Watch is facing quality control issues resulting in manufacturing defects — Taptic Engines that rapidly stop producing haptic feedback. Time was I'd link to reports like these from major business publications without a second thought, but after years of erroneous device delay rumors, misleading Apple Pay headlines, and other questionable coverage from what should be trusted papers of record, I've learned to take some time and look into things first. In this case, Daisuke Wakabayashi and Lorraine Luk both have solid reputations, so the report is absolutely worth noting. From the Wall Street Journal:
A key component of the Apple Watch made by one of two suppliers was found to be defective, prompting Apple Inc. to limit the availability of the highly anticipated new product, according to people familiar with the matter.
The part involved is the so-called taptic engine, designed by Apple to produce the sensation of being tapped on the wrist. After mass production began in February, reliability testing revealed that some taptic engines supplied by AAC Technologies Holdings Inc., of Shenzhen, China, started to break down over time, the people familiar with the matter said. One of those people said Apple scrapped some completed watches as a result.
Taptic engines produced by a second supplier, Japan's Nidec Corp., didn't experience the same problem, the people said. Apple has moved nearly all of its production of the component to Nidec, these people said, but it may take time for Nidec to increase its production.
It should be made clear that we've seen no widespread accounts of Taptic Engine failure on social media or through other channels.
Right now, it's one data point, and as long as your Apple Watch is working, it's not something you need to be concerned about. If you're still waiting to receive your Apple Watch, then unless and until your shipping window changes, it's likewise nothing to worry about.
If you're looking for something to blame for the long shipping times, then maybe this is it, maybe not. Problems with suppliers happen to every vendor, especially large scale vendors, from time to time. They're frustrating for everyone, but alternate plans get made and products still get pushed out.
We'll update as we learn more.
Update: The Wall Street Journal has updated to say there's no indication any defective Taptic Engines reached customers.