Error 405 and 420

I keep getting the error messages (420) Power supply furnace impedance error: value = 53.88, min = 0.00, max = 50.00 (405) Power supply furnace impedance error Instrument: TGA Q5000 I have restarted the TGA parameters in the Service Menu, I have replaced the four quartz bulbs with new ones, I have performed the Auto Diagnostics in the Platinum Menu: Autosampler, Furnace, Mass Flow Controllers, Sample Pan Load/Unload, and Impedance passed the test but the IR bulb check failed this test. The sample temperature readout on the control panel appears normal.