Went and had a look. Airbox didn't 'need' to come out to fix it, but I only noticed the split becuase the box was out, if that makes sense. The pipe in question terminated on top of the intercooler to turbo hose. The hose that had split was...
I had the exact same problem and same error code on my disco 2 td5. I only found the problem by accident - a split in one of the hoses under the airbox. Skinny little hose - think it was a vacumn line but can't remember now. Cut 10mm off it...