Samsung Multifunction Printer Error Code #04-002

Error #04-002 means the LSU (Laser Scanning Unit) motor is not operating correctly or its drive signal is abnormal. The LSU motor spins the polygon mirror that steers the laser beam during printing. When the control board cannot confirm that this motor is running at the correct speed, it triggers this fault and stops printing to prevent damage.

A simple power cycle or factory reset will not clear error #04-002 if the underlying hardware fault is still present. The printer checks LSU motor operation during every startup sequence, so the error will return immediately if the motor or its signal circuit remains defective. The hardware issue must be resolved before the code will clear permanently.

Repair costs depend on the root cause. If only the harness connector needs reseating or replacement, costs are minimal, typically in the range of $10 to $40 for parts. If the full LSU assembly requires replacement, parts and labor can range from $80 to $250 or more depending on the printer model. Main board replacement, if needed, can push total costs higher, sometimes making repair less economical than replacement for older units.

Some basic checks are within reach for a technically inclined user, such as inspecting and reseating the LSU harness connector. However, if the LSU motor itself has failed or the LSU assembly needs replacement, this repair involves handling precision optical components and is best performed by a qualified technician. Improper handling of the LSU can cause additional print quality problems.

The printer will typically refuse to print while this error is active, which is intentional. Attempting to force operation with a malfunctioning LSU motor could potentially cause additional damage to the laser scanning unit or related components. It is best to leave the printer powered down until the fault is diagnosed and repaired.