Printer Faults - Paper Jam Light

The paper jam light means the printer has - or thinks it has - a paper jam

The kind of low cost printer that has a paper jam light usually has just a couple of detectors - one just after the paper pickup and feed roller and another at the fuser exit. Software in the printer times how long after it initiates paper feed, before the detector operates. If it takes too long this assumes paper isn't moving properly. Likewise once printing starts the fuser exit sensor should move in a given time.

Printers don't actually "know" when they have a paper jam, rather the software assumes so from the timing of the detectors.

It is possible to get a paper jam with some printers by having the paper size settings wrong in the computer driver. The printers timings for how long the paper is will be wrong in turn.

Another possibility is that there is a piece of paper swarf caught inside the machine. Take the cartridge out and check.

The wrong grade of paper will cause persistent misfeeds. Laser printers are designed with 80gsm standard office copy paper in mind. Normally they tolerate a range of paper weights from 70gsm to 120gsm, sometimes higher. Printers don't work well with lightweight paper because it isn't stiff enough to feed through the paper path properly.

Lights that don't seem sensible can also be a warning that something problematic has happened. For instance if the "attention" light is also on, the pair of lights together may mean something like "fuser fault".

Obscure light messages have to be looked up in the user guide. If you don't have the user manual (in a heap of discarded CDs, search engines are often helpful. A phrase such as -

• "aculaser C900" "reference guide" filetype:pdf
• "Laserjet CM4540" "user guide" filetype:pdf

Some manufacturers are more benevolent than others in making user manuals easy to find online.