Gen 2: 2000-2004
I've recently swapped an EZ30D (first-gen, alloy manifold) from an Outback into my 2003 Forester, and have just this P0154 code lingering, despite replacing both of the O2 sensors since the previous ones had dud heaters (P0031 & P0051 were the only codes before I pulled the engine).
Here are...