This error indicates that the integrated ambient light diffuser is still in place over the meter lens, blocking its ability to take measurements of emissive displays.

The C6 HDR2000 (and other meters) includes an attached white disk diffuser for use when taking ambient light measurements or measuring direct light sources such as a projector in direct view mode. In all other modes, the diffuser is not used.

For SpectraCal C6, SpectraCal C6 HDR2000, Portrait Displays C6 HDR2000, and X-Rite i1Display meters the diffuser pulls slightly away from the housing and rotates around to the back of the housing (over the tripod mount).