Then the sensor may be measuring the exact RPM (Revolution Per Minute) of each fan and perhaps found No.1 relatively low. It is, unfortunate that I am not able to locate a service manual for SP-H03 model. If you could, you would try to swap the fan No.1 with another one similar it and again power the projector up and see if you get the same error. Lastly, I honestly trust that you may be able to avail the best help by reaching out to the folks at Justanswer.com - it is a paid service but they may just have the service manual thereof handy.