Brother Laser Printer F20 Error Code Fix

by

What This Error Means

F20 on a Brother laser printer usually points to a fuser warm‑up / low‑temperature fault.

Translation: the hot rollers that melt the toner into the paper are not getting up to temperature fast enough, so the machine locks itself out.

Official Fix

Brother’s official line for fuser‑type errors is basic: reset the power, check for jams and airflow, then call for service if the code comes back.

  • Turn the printer off using the power button.
  • Unplug the power cord from the wall. Leave it unplugged at least 10–15 minutes so the fuser cools and the thermal protection can reset.
  • While it cools, pull out all paper trays and remove any obvious jams or half‑melted sheets from the paper path (front, rear, and under the toner/drum).
  • Make sure the side and rear vents are not jammed up against a wall, clogged with dust, or blocked by anything.
  • Plug the printer directly into a wall outlet, not a cheap power strip or long extension cord. Weak power can cause fuser warm‑up errors.
  • Power it back on and run a small test print.
  • If F20 pops straight back up, the manual’s answer is: stop and have the fuser unit or the printer serviced or replaced.

The Technician’s Trick

This is the stuff a field tech does when the basic reset does nothing.

  • Kill the power properly. Turn the printer off, unplug it, and give it a solid 30 minutes so the fuser is stone cold. Do not grab the fuser while it is hot – it will burn you.
  • Get to the fuser. Open the rear cover. On most Brother lasers, the fuser is the big assembly with two rollers and colored (often blue) release levers. If there is a rear duplex unit, pop that out first to expose the fuser.
  • Pull the fuser out. Release the two latches or screws, then slide the fuser straight out using the plastic handles. If it does not move, stop and look for a hidden latch; do not pry on bare metal.
  • Hunt for the obvious cause. Check for:
    • Scraps of paper jammed in the ends of the rollers.
    • Melted labels, tape, or glossy stock baked onto the hot roller.
    • Heavy toner buildup on the small sensor “eye” or the thermistor tab that rides on the roller.
  • Clean the sensor area. With a dry, lint‑free cloth or a folded piece of plain paper, gently wipe toner and dust off the sensor area and the roller surface where the thermistor touches. No alcohol, no spray cleaners, no wet wipes – liquid on the fuser is a fast way to kill it.
  • Check the wiring. Follow the fuser’s cables to the connector on the frame. Make sure the plug is fully seated and not browned, cracked, or melted. A loose or cooked connector can throw F20 even when the fuser itself is okay.
  • Re‑seat everything. Slide the fuser back in until it is fully home and locked. Reinstall any duplex unit and close every cover firmly; half‑latched covers can stop the fuser from powering up.
  • Test on a known‑good outlet. Plug the printer straight into a solid wall outlet, turn it on, and run a small print job.
    • If F20 is gone and prints look normal, you probably had a dirty sensor, partial jam, or loose connector.
    • If F20 returns immediately, the fuser’s heater or thermal sensor is very likely bad – replacing the complete fuser unit is the normal fix.
    • If a new fuser still gives F20, the low‑voltage power supply or main board is failing. That is board‑level work and usually not worth it on cheaper models.

One more inside note: some Brother models latch a fuser error until it is cleared in a maintenance or service menu after you fit a new fuser. If the hardware is new and installed correctly but the code will not clear, that is service‑menu territory – typically a job for a shop with the service manual.

Is It Worth Fixing? (The Financial Verdict)

  • ✅ Fix: Mid‑range or business Brother laser under ~6–7 years old, clean shape otherwise, and a fuser unit costs less than about half the price of a similar new printer.
  • ⚠️ Debatable: Small home/entry models where the fuser is pricey, or the printer is 7–10 years old and already has other problems (jams, noise, faded or streaky prints).
  • ❌ Replace: Very old or bargain‑bin machine, visible heat damage or cracking on the fuser, or F20 still comes back even after a new fuser – board or power‑supply repairs usually cost more than the printer is worth.

Parts You Might Need

As an Amazon Associate we earn from qualifying purchases.

See also

Dealing with F‑codes or weird faults on other gear too? These guides can save you some hunting: