Diagnostic Tips for the  HP Color LJ M551, M575 50.12 Fuser Error Message Â
The LaserJet M551, M575 50.12 Fuser Error is related to the pressure release part in the fusing assembly. There is a cam in the back of the fuser that releases pressure on the pressure roller. There is a sensor arm that rides on the cam. As the cam moves the flag moves and the sensor senses this. Obviously if the cam doesn’t move properly or the sensor flag breaks then you will get this error. Most times I see 50.12 fuser errors once the machines get some age on them. The cams tend to turn really hard and with age they turn even harder. This can lead to improper timing when the cam is released or engaged.
Service Manual Tips for the  M551, M575 50.12 Fuser Error
Fuser pressure-release mechanism failure
1. Remove and then reseat the fuser. Make sure there is no residual paper in the fuser.
2. Check the fuser pressure-release sensor flag. If it is damaged, replace the fuser.
3. Use the sensor test in the Manual sensor test to verify that the fuser pressure-release sensor (PS7) is  properly functioning. If it is not, replace the fuser.
4. Use the fuser pressure-release drive test in the component test to verify that the fuser motor (M2) is  properly functioning. If it is not, replace the fuser motor (M2).
5. If the error persists, replace the fuser. – Â
6. If this product has been previously serviced, check the connector (J117; J123) on the DC controller PCA.
Click on the link below for the fuser removal procedure
HP Color LaserJet M551 – M575 Fuser Removal and Reset
