Develop C3721 error: what it means
C3721 points to a fault with the fusing heater lamp, so the unit cannot heat up properly.
What C3721 means
The fusing heater lamp supplies the heat that fixes toner to the paper. C3721 means the machine has found a problem with it, so printing is blocked.
Applies to: Develop ineo and Konica Minolta bizhub colour machines. The exact wording of a code can differ between models.
Common causes
- A failed heater lamp
- A worn fusing unit
- A wiring or connection fault
What you can safely try
- Switch off and let the machine cool for at least 30 minutes.
- Switch on again. If the code returns, do not retry.
Don't open the machine or touch the fusing unit. It gets very hot and has live parts.
When to call an engineer
Call an engineer. The fusing unit needs checking or replacing and must not be opened by users.
Stop being the person who deals with fault codes
On a CBE lease we can keep an eye on your machine remotely, so we often know about a fault before you do, and an engineer can be with you fast. You also get a 3-hour engineer response. Already in a contract? We can buy you out.
Remote monitoring only picks up some error codes, not all of them, so we can't promise to spot every fault before you do. Ask us which ones apply to your machine.
Frequently asked questions
Can I keep using the machine with a C3721 error?
Usually not. The machine normally locks out printing until the fault is cleared. Try the safe checks on this page once; if C3721 returns, stop and call an engineer rather than forcing it.