It’s no secret that Canon inkjet printers have a couple of cry wolf failure modes that claim to be the end of life for the printer, but are repairable with no parts or special tools. The most common one is the ink disposal error where a software counter expires the silly thing, but it’s resettable… Although Canon would like you to think it isn’t.
Anyway, our trusty Canon MX490 shut down yelling “needs service, B202”. Canon’s official support document says this means it’s dead or at least that you have to replace the cartridges because they “overheated”.
I have been working on inkjet printers since the late 90s and have literally never heard of this failure mode. Furthermore, I’ve never seen a printhead actually do anything close to burning out– at worst sometimes one has had a really stubborn clog, and leaving it lying on a paper towel soaked with distilled water revived it. (Isopropyl alcohol works too but I swear water does it better!)
Radio Shack even used to sell a kit for cleaning the printhead that had a little strip of microfiber brush material and a pen filled with distilled water to wet it with then stroke the head across it. It worked fine but after I figured out a paper towel worked better on certain cartridges I just went low tech.
Anyway, the other part that needs to be clean for correct operation of an inkjet cartridge or printhead module is the electrical connector between the head and the rest of the printer. There’s a matrix of little yellow metal dots or squares on the cartridge, usually on the side that faces the back of the printer. Grab a cotton swab and isopropyl alcohol and clean this, then GENTLY dab clean the matching contacts on the printer carriage, being careful not to snag and bend any parts.
This fixed the printer! No cartridge replacement was needed, I powered it up, it returned the carriage home, did a quick cleaning cycle, and returned happily to service like nothing had ever happened.
Anyway, usually you can access these areas by just sliding the cartridge gently into reach with the printer powered off. Please be warned you may touch ink goopus while doing this. If it’s not possible to move the carriage into reach, you may need to start the printer doing something and yank the power while the head is out of its home position. I don’t know if any Canon machines are like this, but on the old HP Deskjet 600-700 series the cap assembly that seals around the printhead when not in use was raised up by a motor and firmly locked the carriage in the home position. (Sounds like a nice measure to prevent shipping damage!)
On most printers including this MX490, just sliding the cartridge towards the middle uncaps it. If you’re in there, you can also clean the caps and squeegee blades that are near them, this may cure lingering print quality issues like banding or stray ink drops/blobs.
I mentioned specifically cleaning the cartridge contacts with isopropyl alcohol because Hewlett-Packard once had a service note out recommending it – they had a lot of some sort of lubricant (dielectric grease?) that was being factory applied to new cartridges that turned out to be a little too good at maintaining a film between the metal surfaces, causing the cartridges to print poorly or not at all. Their fix was to clean it off. On my printer, it removed visible ink deposits just as well.
If you happen to be here because you’re trying to clean the printhead, please be sure to wipe the squeegee and cap and, if present, clean the two concave grooves adjacent to the printhead with a wet swab. Otherwise you’ll wind up with the head getting re-gooped immediately upon putting it back in, and you don’t want that.
Yes, I need to revise this with pictures, but for now, here’s an unrelated image: