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SwiftRacer Roomba Diagnostics Articles


Roomba Red Diagnostic Mode

Ver 2005.03.15 By Dave Tufte with minor editting by George McQuary, hosted on

For information purposes only. No guarantee of accuracy. Not an employee of iRobot, merely a customer. Not responsible for warranty violation, injury, damages.

To proceed, you are doing so at your own risk; and, agree to the above disclaimer statement.

Please don't ask either of us to fix your roomba. :-)


The information listed below is old and incomplete. It is retained for informational purposes only. Please use the following link for the updated procedures.




First, if you've got battery problems the diagnostic mode won't help you. The solution to that is to make sure the unit is fully charged. If your battery isn't able to hold a charge then your battery is old and needs to be replaced. After that the most common problem is the unit being dirty and having fuzz or hair trapped somewhere it shouldn't be. Try cleaning it --compressed air works great! Assuming you’ve already cleaned your Roomba and are still seeing problems, here’s how to access the Diagnostic Mode.

Entering Diagnostic Mode
First, remove your Roomba from all battery chargers. The safeties that prevent battery overheating are overridden in Diagnostic Mode so unplug the unit from the wall charger/remove it from its charging station.

Hold down Spot and Clean, then press Power briefly and wait ten seconds (this is so it won’t accidentally turn on and run off your tabletop) and it will give you a five note ascending scale.  Then the Red and Blue LED lights will begin to flash.

You can now cycle between the diagnostic modes by using Clean to advance in the sequence, and Spot to return to the diagnostic mode before. This only works for the first four diagnostic modes, the rest are multi-stage and Spot only takes you backwards within that diagnostic.

Mode 1 (1 beep) Bumpers and Wall Following Mode.

Pressing the Left side of the bumper turns the Spot light on.Pressing the Right side of the bumper turns the Clean light on.

The IR sensor on the right side bumper can also be tested, and will flash both buttons (it has to be very dark to trigger).

Spot or Clean Failure: You’ve got some fuzz blocking the bumper's optical sensor holes and need to clean them out.
IR failure: Clean the IR light and IR detector in the right side of the bumper.

Mode 2 (2 beeps) Left IR cliff edge sensors. RIGHT SIDE IS IGNORED

Put the roomba on a table. Slowly move the left side of the roomba off the edge while holding it in your hands. Hold it by the sides --holding it by the front bumper will block the IR sensors. The two IR sensors in the left side of the bumper will light when there is nothing beneath them.
Left bumper IR light: Clean light.
Left bumper IR in center/front: can be triggered seperately if you are careful.

Failure: Clean out the IR sensors in the front bumper of any fuzz. If you think an IR light is blown, try using a digital camera to see the IR light --most cameras can see IR quite well.

Mode 3 (3 beeps). Right IR cliff edge sensors. LEFT SIDE IS IGNORED

Put the roomba on a table. Slowly move the right side of the roomba off the edge while holding it in your hands. Hold it by the sides --holding it by the front bumper will block the IR sensors.
Right bumper IR light is Spot light.
Right bumper IR in center/front: Can be triggered seperately if you are carefu.
Left side is ignored.

Failure: Clean out the IR sensors of any fuzz.

Mode 4 (4 beeps). Extension of Wheels, Virtual Wall, and Remote

Spot will light on full extension of any of these three: the front wheel, the left wheel, and/or the right wheel. By allowing these to extend one at a time, you can check all three sensors. (You may wish you had three hands to make this easier.)

Failure: Clean the center wheel extender sensor, the left wheel extender sensor, and/or the right wheel extender sensor.


Mode 5 (5 beeps) is Move Straight Forward. Both wheels rotate straight forward ignoring all sensors and safeties. There are no safety features turned on!

Press Clean and you get 1 beep as a warning. Press clean again to enter this diagnostic and get another beep. This is immediately four beeps (short, long, short, short) and a motor will start to spin the unit counterclockwise.
Press Clean again and you get 4 beeps (long, short, short short) and it will spin clockwise.
Press Clean again and you get 5 beeps (long, short, short, short, short) and it will go straight backwards. Spot flashes with left wheel turning, Clean flashes with right wheel turning.
Press Clean again and you will get two short beeps. Spinning the front wheel manually will cause SPOT to be green for a quarter turn and dark the rest of the turn.

Failure: (check with mode 6 also)

If a wheel isn't moving, you've probably gotten a broken belt. If travels worse than a 45 degree from straight ahead on the floor (say in circles), you've probably got belt slippage from a worn belt. Within 45 degrees or less from straight ahead is considered acceptable belt wear by most owners and the Roomba has been found to clean just fine. Not flashing is a failure, and usually means either fuzz on the optical sensor keeping it from seeing or a broken belt. (It's under a dollar to replace). Check the article Roomba Belt Replacement if not flashing or belt slippage.

Mode 6 (6 beeps), Optical Rotor Test. Straight reverse both wheels plus optical sensor output for each wheel.

Press Clean and you get three short beeps. The brushes rotate.
Press Clean again and you get four short geeps and it turns counterclockwise while turning the brushes.
Press Clean again and you get five short beeps and the vacuum runs.
Press Clean again and you get six short deeps and the side brush spins.

Mode 7 -10

Unknown still. Just press Clean to advance through them. Sequence is 4 beeps, 5 beeps, 6 beeps, seven beeps, four beeps, five beeps. .

To exit Diagnostic Mode: Get back to "Start Test" mode where all lights on and flashes left to right. Press power again to exit test mode. Or just remove and replace battery.

When the diagnostic tests are done the red battery light will flash very quickly. These tests are used on the assembly line from a power supply. Remove your battery and put back in to end diagnostic mode. This unit also changes between two tones when it beeps. I think this is just to make it easy to count them, since they can all be differentiated by the number of beeps too.

I haven't bought the Discovery model yet so the only information I have is courtesy of other Roomba owners. Please let me know if other Discovery models are different.

Michael Tannenbaum also write of the Discovery:

They have changed the diagnostic coding with the Discovery model. When you first access the mode all the lights flash. A little melody plays and the blue dirt status light begins to flash. Beep one is as your article states but only the spot and clean buttons indicate sensor activity, Center is indicated by both buttons lighting. You go up one step by pressing clean and down one step by pressing spot. Codes 1 through 4 act as described in your article. Then there is a long tone and a pause the codes above function as follows:
01 Bumpers and Wall following mode
02 Left IR cliff edge sensors
03 Right IR cliff edge sensors.
04 Extension of Wheels, Virtual Wall, and Remote
11 Lights on
12 Left wheel motor
13 Right wheel motor
14 Both wheel motors
20 Pause
21 Main Brush
22 Main Brush and both wheels
23 Vacuum
24 Wall sweeper side brush
30 is a pause and above 30 there are dianostic steps but nothing appears to happen. The max button does not seem to do any thing.

See also the articles: Roomba Diagnostic Songs, Roomba Belt Replacement, Roomba Problems.

[Other contributors: Michael Dwyer, Mike Tannenbaum, Dave Tufte]

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