Canon E240 — Main controller / DC controller communication error

What this error means

The machine's two main brains stopped talking — a fault between the main controller and DC controller boards. Board-level; beyond a power cycle there's no user fix.

Symptoms

• Error at boot
• Machine freezing mid-job

Try this first (safe DIY steps)

1. Power off at the main switch, wait 60 seconds, power on
2. If it recurs, note the full code (including any detail digits) for the service call

Safety: power off before any physical intervention. Never bypass covers or interlocks — fuser areas run hot enough to burn.

When to call a technician

Promptly — board or harness diagnosis.