I have a Hp Photosmart Plus - B-210 printer.  It says there is a ink system failure, new cartridges, and gives this: oxc19a0042,  then says turn printer off and on.  Nothing changes when comes back on.  Any suggestions ???

Have you tried these already?

Reset the Printer:
1. Switch on the unit.
2. Open printer and remove all cartridge.
3. Unplug the power cord from the printer.
4. Unplug the cable from the wall outlet
5. Wait 30 seconds.
6. Plug the power cord back into the printer.
7. Plug the power cable directly to the wall outlet.
8. Open the top cover and reinsert the cartridges.
9. Turn the unit on.
10. Print a document to test

If resetting the printer didn't work, check and clean the printhead:

How to remove the printhead:
1. Press the Power button to turn on the product.
2. Open the cartridge access door.
3. Remove each cartridge.
4. Lift the latch handle on the carriage until it stops.
5. Lift the printhead straight up to remove it.

How to clean the printhead:
1. Plastic ramp on the side of the ink nozzles
2. The edge between the ink nozzles and the electrical contacts
3. The electrical contacts
Do not touch the ink nozzles. Use only cleaning materials to touch the electrical contact areas.

Re-install the printhead:
1. Raise the latch handle, and then reinsert the printhead.
2. Carefully lower the latch handle before reinserting the cartridges. The latch must remain down to install the cartridges correctly.
3. Slide the cartridges into their appropriate slots until they snap firmly into place in the slot.
4. Close the cartridge access door.

If those didn't work the printhead is broken, either buy a new printhead or new printer.