A 50 service error indicates a problem with the fuser assembly, this is the part of the printer that fuses (melts) the toner into the media. It consists of a heated roller or film and a pressure roller along with drive gears and sensors. It is subject to mechanical wear and thermal degradation. Most newer models have solid state thin film heating elements rather than the halogen lamps in older machines. These heating elements are subject to failure from burned resistive heating paths and fractures of the ceramic substrate material. There are typically two sensing elements, a thermal fuse to prevent catastrophic overheating, and a thermistor to provide feedback to the heating circuit and indicate when to turn the heating current on or off. It is important that replacement fusers use proven and tested replacement materials. Our remanufactured fusers use first quality replacement parts and ISO 9000 standards in the remanufacturing process.

50 Service errors can also be related to the power supply or control circuits. In many machines the fuser is a maintenance item and the major component of a maintenance kit. You can Self maintain your printer and save.  Support for our customers is always available via email and live chat.

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Common To Most Newer HP Laserjet printers
HP LJ 8150 50.1 Fuser Error
HP LJ 4/4M and HP LJ 4+/4M+/5

•Common to HP Laserjet Printers

50.X FUSER ERROR alternates with For help press ?
A fuser error has occurred.
X Description
1 - low fuser temperature
2 - fuser warm up service
3 - high fuser temperature, fuser over temperature
4 - faulty fuser
5 - Incorrect fuser installed
6 - Open fuser circuit
8 - low fuser temperature (subthermistor)
9 - high fuser temperature (subthermistor)

This error usually indicates a defective fuser.  Turn off printer for 20 minutes (to allow internal error circuit to reset) and try again. If the error persists, it could be due to a faulty thermistor, fuser heating element, or loose or open connection to the fuser. Sudden occurrences are almost always the fuser assembly. The fuser assembly may be hot, allow to cool before removing it from the printer or injury may result. You can perform a heating element test by checking the resistance between the two heavy leads in the fuser connector. Resistance should read less than 100 ohms in most cases, an open circuit indicates a defective fuser. For low fuser temperature errors, check the smaller leads on the fuser connector to measure the thermistor resistance. At room temperature, you should read in the range of 50Kohms to 350Kohms at room temperature. It should not be an open circuit nor should it appear as a short circuit. In some cases this error can also be caused by a defective power supply or faulty DC controller board, but check the fuser first. The most cost effective method of repair is to replace the fuser assembly. Component parts are not readily available and fuser repair can become involved. Also be aware that early replacement of consumable fusers may require reset of the internal counters so the maintenance interval remains correct. Replacement fuser assemblies are available here- Fuser Assemblies or it may be time to consider a Maintenance Kit which contains the fuser assembly.

•HP LaserJet 8150 Error 50.1 Fuser Error
This error indicates a low temperature condition which we have found this to be the low voltage power supply, part number RG5-4357. Check the fuser resistance first to confirm, but most times it will require replacement of the low voltage power supply.

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•HP LJ 4/4M & HP LJ 4+/4M+/5
On the HP Laserjet 4/4M/4+/4M+, most suspect is the halogen lamp. The thermal fuse and thermistor are also possible causes of a 50 Service error. You can remove the fuser assembly from the printer and measure the resistance of the lamp/thermal fuse circuit - it should be less than five ohms. As these printers age, power supplies are becoming more common as the cause of 50 Service Errors.

Measure between the two heavy gauge pins on the fuser assembly connector. If you measure an open circuit, the problem is most probably the lamp. Removal of the lamp, although not difficult, requires knowing where the snaps are located to remove the plastic covers. When you purchase a lamp we can email instructions.
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