It subsequently became apparent that even for the Celeron the Tualatin would be no more than a stopgap, only taking the range to 1.5GHz. At that point it became apparent that the plan was for the Pentium 4 Willamette core to move to the value sector, address the long-standing FSB bottleneck and take the Celeron family to 1.8GHz and beyond. The first Pentium 4 based Celeron duly arrived in May 2002.
Based on the 0.18 micron Willamette core, the next series of Celerons were, in consequence, a completely different design. Often referred to as Celeron 4, they had 128 KB rather than 256KB or 512KB of L2 cache, but are otherwise very similar. Their performance suffered considerably as a result of their smaller caches and in general, this first generation of P4-based Celerons were not well received. However, some speed grades were favoured in the enthusiast market, because like the old 300A, they ran well above their rated speeds.
By the end of 2002 the Celeron had been upgraded to the 0.13-micron Northwood core, allowing it to run at much higher speeds and cooler than before. However, even with a full 512K L2 cache in the Northwood design, Intel stuck with the 128K cache for the Celeron 2.0 GHz and the new Celeron remained stuck on the 400 MHz bus.
The last and fastest Northwood-based Celeron was released in the spring of 2004, clocked at 2.8GHz