Diagnostic Information on the  Lexmark T654, T652, T650 Error Code 920.03
Like so many of these newer machines this is yet another of the fuser related error codes. The  Lexmark T654, T652, T650 Error Code 920.03 message means the temperature reported on the hot roller registered cooler than expected in slope change in standby mode. Below you will find some diagnostic information that the service manual has to say on this subject. Also, I have added a few personal tips that have helped me on occasion when dealing with related fuser issues.
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40X4418-FRN -N Lexmark Fuser T650 T652 T654 X65X Factory Rebuilt With All Oem Parts T650 X652
Service Manual Diagnostic Information on the Error Code 920.03
Lexmark T654, T652, T650 Error Code 920.03 Fuser warm-up failure – Fuser type = 1
The fuser hot roll is too cool  while checking for slope  change in standby.
1. Turn the machine off/on  and ensure the fuser unit  assembly is properly  installed.
2. Ensure the proper voltage  fuser is installed in the  machine.
3. Replace the fuser unit  assembly if problem  remains.
Additional Diagnostic Information
1. Sudden power outages or brown outs can cause errors like this because the machine can switch modes suddenly and read an incorrect temperature. If this is the case then turning the machine off then back tends to correct the issue.
2. No power strips or battery back ups. Like step 2 in the service manual advice, this leads to incorrect power problems. These machines consume a lot of power in very short amounts of time. Like a cold car battery, if you don’t have enough amps, then you have issues.
3. Reseat the fuser. Remove the fuser and clean the surface of the thermistors and make sure they are making contact with the surface of the pressure roller.
4. Replace the Fusing Assembly.
Click on the link below for the fuser replacement instructions
Lexmark T654, T652, T650 Fuser Assembly Replacement – 40X4418