Epson 4900 pro color dropped color channel

We have three Epson 4900 Pros that see a lot of heavy use. One of these printers had the yellow channel drop out of the nozzle checks and I have been tinkering with the printer for the past several months to try and revive the machine. Note that throughout this process we have run countless normal and power cleanings, taking care to not run too many per day to avoid overheating the printhead.

Nozzle checks return perfect except for the yellow channel which only produced 12 or so lines in the printed check. At first it was suspected to be an issue with the ink pump, so we replaced the ink pump, but this had no effect on the nozzle check. At this point we assumed that it was a dead printhead. I ordered a new printhead and installed it.

The new printhead was initially doing great but while running through the adjustment program for a print head swap the yellow channel dropped out, again printing only a couple lines per nozzle check. I cleaned the flushing box, head caps, and the wiper. I performed a headsoak with piezoflush, and tried swapping ink cartridges to ensure that there was not a factory defect in the cartridge causing my issue. When these steps yielded no results I tried filling a cartridge with piezoflush and running that through the yellow channel. After a couple power cleanings, the piezoflush made it all the way through the inkline and is showing up in the nozzle check.

At this point there were still only a few lines produced in the yellow channel (printing piezoflush now) of the nozzle checks. I tried swapping back in the old printhead and confirmed that it was still the yellow channel causing my problems. Being the last part between the ink cartridge and the paper, I suspected that it might be an issue with the damper assembly, so I ordered and replaced that unit. After the replacement I ran the appropriate adjustment program but there was no discernible change in the nozzle check. The nozzle check looks good other than the yellow channel, which is now only producing like 5 lines each check. I am still running piezoflush through the channel and the few lines that do show up in the checks are not consistently the same lines.

Admittedly, I am new(ish) to printer maintenance. Does anyone have any recommendations for how I should proceed? At what point is trying to repair an epson 4900 pro a lost cause?

I appreciate any and all feedback :slight_smile:

Hi Matilda,

I see you’ve been proactive in troubleshooting the issue! Replacing the print head and damper yourself is impressive. To help narrow things down, did you happen to use a fresh yellow ink cartridge after replacing those components, or did you put the same one back in?

By the way, I can see from your account that you’re a valued customer since 2019! You purchased color dye inks and 4900 cartridges in 2021. Is that cartridge and that yellow ink what you’re currently using with this printer?

Rachel - TechSupport IJM


the initial yellow cartridge was a refillable cartridge filled with yellow ink harvested from “empty” epson cartridges. The Replacement Yellow was an official epson cartridge. The piezo flush is loaded into a refillable cartridge.


Hi Matilda,

Ruling out ink is a great first step. Since you’ve seen similar issues with three different cartridges, that’s a strong sign the ink itself isn’t the culprit. Now, considering the new print head and damper haven’t resolved the problem, it’s possible the damper installation might be the key. Less likely, but still worth checking could be the ink selector unit.

New parts for these older models can be tricky to find. Here’s an option you can consider if obtaining a new ink selector unit proves difficult. Since you mentioned having two other functioning 4900 printers, have you thought about temporarily swapping the ink selector unit from one of them to see if that resolves the issue on your problematic printer? This will rule out the damper and the ink selector unit.

It’s getting late, so I’ll circle back tomorrow to help troubleshooting. Perhaps some members of the Community can offer their experience to you tonight.

Rachel - TechSupport IJM

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The last thing i tried in my diagnostic journey was to replace the damper assembly, and that had no effect on the nozzle checks for the yellow channel.
:sweat_smile: It took me bit of confused research but the ink selector unit is integrated into the damper assembly in this model of printer. so that part is new and its replacement made no impact on the issue.

I appreciate all the troubleshooting steps you’ve tried to get the yellow ink working. Based on what you’ve described, it seems like the issue might be located somewhere before or after the ink selector unit.

Let’s break it down:

  • Printhead: Since you’ve tried a new printhead and the yellow issue persists, we can likely rule that out unless, by very low chance, the new printhead also had a faulty yellow channel.

  • Ink Selector Unit: It sounds like you’ve replaced the selector unit, and also replaced the yellow damper in it to rule this out, so that’s good news!

  • Ink Delivery System: This leaves you with a couple of possibilities. You already wrote with confidence that you do not believe you have bad ink. But, there always remains that possibility. Although if bad it may have already killed your replacement damper and that will require There could be a blockage or issue with the ink line that delivers yellow ink to the printhead. You could try some PiezoFlush back through the ink line and collecting it from the ink stem in the ink bay or visa versa to rule that out.

  • Electronics: It’s also possible there’s an electronic issue preventing the yellow ink from being used. Unfortunately, troubleshooting electronics is a bit beyond my scope or anything that I can recommend. It might be best to reach out to a qualified printer repair technician to take a closer look at the electronics.

Rachel - TechSupport IJM