Sony's PSN woes aren't over just yet. The company has temporarily stopped taking PlayStation promo codes following a surge in traffic on the gaming service; for the moment, money cards and game vouchers won't work. There's no estimate for when code redemption will return. It's easy to see the potential causes, however. Between the weekend, the PlayStation 4's European launch and a big discount on PlayStation Plus subscriptions at Amazon, there's guaranteed to be a deluge of PSN activity -- Sony may have unintentionally created a perfect storm.
Source:PlayStation Community Forums