my hp laserjet pro mfp m234dwe is smearing toner all over the pages

Diagnosis

Toner smearing on the HP LaserJet Pro MFP M234dwe is almost always a failure of the fuser assembly to permanently bond the powder to the paper, or a failure of the primary charge roller to clear excess toner. When the fuser's heating element or pressure rollers are compromised—either by a buildup of "toner crust" or a worn-out Teflon coating—the toner remains in a powdered state and smears across the page as it exits the machine. This often manifests as "ghosting" (repeating patterns) or long vertical streaks of grey or black. Another common culprit is a leaking toner cartridge (HP 136A or 136X). If the seal on the hopper has failed or the developer roller is damaged, excess toner spills into the transfer belt area. You can confirm if the issue is the fuser by performing a "half-way" test: start a print job and pull the power cord exactly when the paper is halfway through the machine. If the toner is smeared before it reaches the fuser rollers, the cartridge is the problem. If the image is crisp until it hits the fuser, the fuser is the root cause.

How to Fix It

To resolve smearing caused by residue buildup, you must perform a deep cleaning of the fuser and the internal paper path. Follow these precise steps:

1. Obtain the printer's IP address by pressing the "Information" button (i) on the control panel to print the Network Configuration Page.
2. Open a web browser on a computer connected to the same network and type that IP address into the address bar to access the Embedded Web Server (EWS).
3. Navigate to the System tab in the top navigation menu.
4. Click on the Service sub-menu on the left-hand sidebar.
5. Locate the Fuser Cleaning section and click Start. The printer will feed a specialized cleaning sheet through the rollers to lift off debris.
6. Once the cycle is complete, open the front access door and remove the HP 136 toner cartridge.
7. Inspect the transfer roller (the black spongy roller beneath the cartridge area). If you see loose toner powder, gently wipe it with a dry, lint-free microfiber cloth. Do not use liquids or alcohol on this roller.
8. Reinsert the cartridge firmly until it clicks and run a "Print Quality Page" from the HP Smart app to verify the fix.

If That Didn't Work

• Replace the Toner Cartridge: If you are using a third-party or "compatible" 136A cartridge, the toner density may be too high for the fuser to handle. Replace it with a genuine HP 136X high-yield cartridge. If the cartridge is leaking powder into the machine, use a handheld vacuum with a HEPA filter to clean the interior cavity before installing the new one.
• Adjust Paper Settings: If you are using heavy cardstock or labels, the fuser may not be reaching the necessary temperature to melt the toner. Go to the EWS Settings menu, select Paper Settings, and change the "Paper Type" from "Plain" to "Heavy" or "Cardstock." This slows the print speed, giving the fuser more time to bond the toner.
• Replace the Fuser Assembly: If the smearing persists and appears as a consistent vertical streak in the same spot on every page, the fuser film is torn. This is a hardware failure. You will need to replace the fuser unit (Part number varies by region, but typically the fuser assembly for the M234 series).
• Clean the Pickup Rollers: If the smearing is accompanied by skewed pages, the pickup rollers may be slipping, causing the paper to enter the fuser at an angle. Clean the rubber rollers with a damp, lint-free cloth using distilled water only.

Heads Up

• Never use canned air (compressed gas) inside the printer; the high pressure can push toner powder deeper into the optical sensors and electronics, causing permanent board failure.
• Avoid using "generic" toner cartridges that do not have the original HP chip; these often output toner at an incorrect voltage, leading to the exact smearing issues described here.
• Always store your spare toner cartridges upright. Storing them on their side can cause the toner to shift, leading to leaks and streaks upon installation.
• Run a cleaning page once every 1,000 pages to prevent the buildup of "toner dust" on the fuser rollers.