HP LaserJet Pro 400 Printer M401 series - Manual (Page 103)

If the message persists, contact HP support.
79 Service error Turn off then on
Description
An incompatible DIMM is installed.
Recommended action
1. Turn the product power off.
2. Install a DIMM that the product supports.
3. Turn the product on.
If the message persists, contact HP support.
Black cartridge low
Description
The toner cartridge is nearing the end of its useful life.
Recommended action
Printing can continue, but consider having a replacement toner cartridge available.
Black cartridge very low
Description
The toner cartridge is at the end of its useful life. A customer configurable option on this product is
"Prompt to Remind Me in 100 pages, 200 pages, 300 pages, 400 pages, or never." This option is
provided as a customer convenience and is not an indication these pages will have acceptable print
quality.
Recommended action
To ensure optimal print quality, HP recommends replacing the toner cartridge at this point. You can
continue printing until you notice a decrease in print quality. Actual cartridge life may vary.
Once an HP toner cartridge has reached very low, HP's Premium Protection Warranty on that toner
cartridge has ended. All print defects or cartridge failures incurred when an HP toner cartridge is used
in continue at very low mode will not be considered to be defects in materials or workmanship in the
toner cartridge under the HP Print Cartridge Warranty Statement.
Cleaning
Description
The product periodically performs a cleaning procedure to maintain the best print quality.
ENWW Interpret control panel messages 91