iRobot Roomba Error Code 42: How to Fix It

Q: What does Error 42 mean on a Roomba?

Error 42 on a Roomba means the robot has detected a mop assembly fault. This typically indicates that the mop pad tray, mop module, or the mop lift mechanism is not functioning correctly — either due to dirt buildup, a misaligned mop pad, debris in the lift arm, or dirty electrical contacts between the mop module and the robot body.

Q: Can I run my Roomba without the mop module to bypass Error 42?

On Roomba Combo models, removing the mop module entirely may allow the robot to run in vacuum-only mode without triggering Error 42, depending on your model. Check the iRobot Home app settings to see if a vacuum-only mode is available. However, this is a temporary workaround — you should still resolve the underlying mop assembly issue for full functionality.

Q: How often should I clean the Roomba mop pad to prevent Error 42?

iRobot recommends rinsing or replacing the mop pad after every 1-2 cleaning cycles, or more frequently if mopping heavily soiled floors. Regularly cleaning the mop tray and contact pins every 2-4 weeks helps prevent residue buildup that can cause Error 42 and other mop-related faults.

Q: Is Error 42 covered under iRobot warranty?

If Error 42 is caused by a hardware defect — such as a failed mop lift motor or a faulty mop module — and your Roomba is within the standard 1-year limited warranty period, iRobot may repair or replace the unit at no charge. Contact iRobot Support at support.irobot.com with your model number and proof of purchase to start a warranty claim.

Q: Why does my Roomba keep getting Error 42 after I already cleaned everything?

If Error 42 keeps returning after thorough cleaning and reseating, the most likely causes are: worn or damaged electrical contact pins on the mop module, a failing internal mop lift motor, or outdated firmware misreading the mop sensor. Try updating the firmware via the iRobot Home app first. If the error persists, the mop module itself likely needs to be replaced, or the robot may require service from iRobot support.

Abstract

iRobot Roomba Error Code 42 signals a mop assembly fault, meaning your Roomba Combo or mopping-capable model has detected a problem with the mop pad, mop lift mechanism, or the attachment that connects the mopping module to the robot. This can be triggered by a dirty or misaligned mop pad, debris jamming the mop lift arm, or a faulty mop module connection. In most cases, this error is resolved with a thorough cleaning and a proper reseating of the mop components — no professional repair needed.