How to Fix HP "49 Service Error" (Including 49.4C02)

Step 1: Clear the print queue

The most common trigger is a specific print job the printer couldn't correctly interpret — often a particular PDF or a job sent while a driver or firmware mismatch existed. On your computer, open the print queue for this printer and delete every pending job, even ones that appear to have already printed.

Step 2: Power cycle with the network cable disconnected

Turn the printer off, disconnect the network/USB cable, then power it back on with no cable connected. If the printer reaches a normal ready state with nothing connected, the error was being triggered by an external job or connection — reconnect the cable and try printing a simple test page rather than immediately resending whatever job caused the original error.

Step 3: Check for and install a firmware update

Some 49-series errors are tied to a known firmware issue with a documented fix in a later firmware version. Check your model's support page for an available update — this resolves the error entirely in cases where it was firmware-related rather than job-related.

Step 4: Remove any add-in memory or accessories

If your model has optional memory DIMMs or add-in accessories installed, and the error persists even with no cables connected, try removing any add-in memory and retesting. A faulty add-in component can trigger this error family in a way that looks identical to a job or firmware problem.

If it persists no matter what

A 49-series error that returns immediately at power-on with absolutely nothing connected, after a firmware update, and with any add-in memory removed, does point toward a genuine hardware fault — most often the formatter board (the printer's main logic board). This is a real, if less common, outcome and generally requires professional service or a formatter board replacement rather than anything fixable at home.