Printer error codes and messages refer to random messages on the Control Panel of an OKI printer. These error codes and messages occur when something in the printer is wrong. These errors can be annoying, but they tell you what’s wrong with the printer. Hence, it’s important to understand the printer error codes and fix them. 

Error 1: Fuser Unit Error (error 543, 544, 545)

A fuser unit is an internal component of the printer that melts the ink on the paper. If this unit is overheated or damaged, your OKI printer will display this error. This error is common in OKI printers that print in large volumes. Over time, the fuser unit can get damaged due to overheating. If this issue arises with your printer, check out the solutions for it. 
 

Solution 1: Restart the Printer 

As this issue is quite technical, restarting the printer is a good way to start. Use these steps to restart the printer. 

1. Press and hold the power button on your printer to turn it off. 
2. Then, disconnect its power cable from the power switch on the wall. Wait for a minute. 
3. Now, reconnect the power cable back to the power outlet on the wall. 
4. Turn on the printer by pressing its power button at the front. 

Check if your printer still shows this error message. A restart sometimes temporarily fixes the issue. So if the issue persists, you should replace the fuser unit. 

Solution 2: Replace the Fuser Unit 

When the error message doesn’t go away, you need to replace it. Check out the steps below to do it. 

Step 1: Turn off the Printer 

Disconnect all the cables, such as USB and power cables, from the printer. This step is important to prevent yourself from an electric shock. Let it be turned off to cool down the fuser unit, as it is usually very hot. 

Step 2: Open the Rear Access of the Printer

The fuser unit is located in the rear of the printer. To replace it, you need to open that cover. You have to pull the rear access door down to open it. 

Step 3: Find and Release the Fuser Unit

The fuser unit is located as a black unit with side clips. You will also see a “Hot Surface” warning in yellow on them. Now, press the blue or green lever on the sides of the fuser unit to release it. As this unit is hot, use a cloth to hold it. 

Step 4: Insert the New Unit 

• Take a new fuser unit and insert it where you pulled out the old unit. 
• Align it properly until you hear a clicking sound. 
• Also, adjust the lever on the sides. 

Step 5: Close the Rear Access Panel

Once you have inserted a new fuser unit into the right slot, lift the rear access panel to close it. Once you close it, you’re ready to use your printer again. 

Step 6: Turn on the Printer

1. As you turned off the printer in starting, turn it on now. 
2. Connect it to the USB cable and the power cable. 
3. Then, press the power button on the printer to turn it on. 

Error 2: Low Toner 

When the ink runs out of toner, the printer will show the error message as low toner or replace toner on its display. Hence, you need to replace the empty toner cartridge in the printer. These toners color your prints, and when any one of them is empty, the printing will not happen, or you will get faded or blank prints. This is how to replace them in four simple steps. 

Step 1: Turn Off the Printer

1. To start, you need to turn off the printer. Press and hold the printer’s power button at the front until the light turns off. 
2. Also, remove its power cord from the power outlet. 

Step 2: Open the Access Door

1. Then, open the access door, which is usually present at the top of the OKI printer. If you can’t find it, refer to your OKI printer manual to check it for your printer model. 
2. Slowly release the cartridges, which are labeled with the color they contain. 
3. Shake them to check if they are empty. 

Step 3: Replace the Cartridge

1. Now, prepare a new cartridge of the color that is empty. To prepare, remove its packaging. 
2. Then, insert it into the right slot. For example, a black cartridge in the black slot. 
3. After replacing the ink cartridges, close the access door slowly. 

Step 4: Turn On the Printer

1. Reconnect the printer’s power cable to the power source on the wall. 
2. Turn on its power button until the green light flashes. 

That’s how to replace the empty cartridges in the printer. 

Usually, these error codes occur when the printer’s connection is weak, ink is running out, printer drivers are outdated, or the paper settings in the printer are not set correctly. But, with the right methods, you can easily fix it, such as power cycling the printer, replacing its ink cartridges, correcting its paper setting, etc.