I have a Canon MulitPass MP730. Wrong Cartridge message.

It's worth repairing, That error on a Canon is saying that the printhead is bad, not your cartridges. The part number for your printhead is stamped on the side of the printhead could be QY6-0049-000 but I'm not sure.

Error: "Wrong Cartridge"
Solution: Clean bedsand Reset the Canon MP370

Preparation 1: Remove ink cartridges
Preparation 2: Clean the bed of each cartridge in the printhead and clean the sensor (I use a cotton bud, experts will cringe)
Preparation 3: On the printhead the light blue/grey lever on top must be all the way to your left as you look at the machine.
Preparation 4: Put back the ink cartridges and make sure each one clicks into place
Preparation 5: Make sure there is paper loaded at the back as normal (in case you've fixed the error but alarm is now blinking because of paper!)

Now Reset the printer:
1. Printer ON
2. Press Additional Functions, Scan, Copy, Scan. to get into Service mode
3. Select Test mode
4. Select #8 Printer Test, it will clean then it says 2 -- 8
5. Press 3 - Says EEPRON Clear.
6. Select 0, Ink count
7. Press OK/Set
8. Select 0, Ink count
9. Press OK/Set (Yes, do it twice)
10. Turn printer Off and then ON

If you make the wrong selection, press the red cancel button with a triangle on it. This takes you back to the beginning of the service menu

Otherwise there is an unlikely chance your printhead is bad, part number: QY6-0064-000 aprox.US$50.00 in 2009