Rudy Winston
Rudy Winston

Rudy Winston has over 14 years experience with Canon USA's Pro Products team, and has been responsible during that time for training Canon's staff on new products, creating presentations for customers and dealers, numerous writing projects, and providing technical assistance to professional and amateur photographers.

Canon EOS Error Messages: An explanation and understanding

February 06, 2012

"EOS digital SLRs can display a series of possible Error Codes, depending on the nature of a detected problem"

The modern SLR has evolved over the past three decades from a largely mechanical device to a highly sophisticated product with computer-like internal operation and control. To the casual observer, it may seem like there’s little more to be concerned about than the position of the on-off switch and the mode dial on the camera’s exterior. But beneath the surface, there’s an incredible network of electronics and mechanical parts that must work precisely together. And in just the same way as a modern computer can sometimes become conflicted internally and “lock-up” or “crash”, requiring a re-start to clear it up, this can sometimes happen to modern SLR cameras as well.

Canon has installed provision to display Error Codes in EOS SLRs for quite some time. Until fairly recently, the camera could basically display a single, or limited range, of these codes to the camera user… today’s cameras do provide a wider range of possible read-outs, giving the photographer at least some idea of possible checks or corrective steps to take if he or she should encounter such a problem in the field.

In this report, we’ll give some insight into what these codes may mean, and possible steps a user can take to hopefully clear the problem in the field, and if that doesn’t work, at least to further isolate it so that only the equipment that needs to actually be sent to a service facility is sent.

A good analogy: the “check engine” light in a car

Like modern SLR cameras, modern automobiles from the late 1990s onward have a sophisticated electronic diagnostic system built-in to detect various problems and inconsistencies in operation. If a disturbance is detected, a “check engine” light will appear on the car’s dashboard, and usually either stay illuminated, or even blink on and off if it’s something severe. The dashboard light doesn’t tell the driver WHAT exactly is wrong… only that the car’s electronic system has detected some sort of disturbance or anomaly. When the car is brought into a service facility, a technician with an on-board diagnostic tool (OBD) can connect the instrument to the car, and get a specific read-out of what that industry calls “trouble codes”. This tells the service personnel where the problem is detected.

Possible error codes in EOS SLR cameras

EOS digital SLRs began by displaying a series of possible Error Codes, depending on the nature of a detected problem. In early years, these codes were quite general. More recent EOS models, such as the EOS 7D, Rebel T1i, and subsequent models, have expanded the possible codes that can be displayed on the camera’s LCD monitor or LCD panel.

Error codes shared by nearly all EOS digital SLR bodies include…

  • Err 01: Lens to body communication error
    The camera to lens communication is somehow being interfered with… could be a problem within the lens itself, possibly the camera body, or something as simple as a smudged fingerprint on the lens mount contacts.
  • Err 02: Memory card error
    There is a problem with communication between the camera and memory card (again, could be within the camera, or the card), or the camera has detected a different error of some sort with the card.
  • Err 04: Card Full
    The camera detects that no space is available for image storage on the memory card… this could be a simple matter of the card literally reaching its capacity, or perhaps some sort of card error where space on the card is not being seen as “available” by the camera.
  • Err 05: Built-in flash obstruction
    The camera detects that the built-in flash has not reached its normal, raised position for flash shooting, and is halting operation until the obstruction to the flash is cleared, or the flash is pushed back down to its OFF position. This error message won’t appear on cameras like the EOS 5D series, which have no built-in flash.
  • Err 06: Self-cleaning sensor malfunction
    The sequence of events during the self-cleaning process is not being detected as completed.
  • Err 99: Non-specific error code
Error 99 — the “check engine light” of previous Canon EOS SLRs

For EOS photographers working with cameras that were launched prior to about 2007 (such as an original EOS 5D, a Rebel XT or XTi, EOS 20D, and so on), this error code generated more misinformation than any other. Contrary to much on-line speculation, Error 99 on EOS models of this vintage was a non-specific error code — much like the Check Engine light in a car. The camera had detected some sort of internal disturbance or error, but it wasn’t precisely related to codes 01 through 06 above. Just because two different EOS cameras of the same model may have reported “Error 99” messages in no way meant that they encountered the same problem… any more than two similar cars with Check Engine lights illuminated were necessarily having the same trouble.

Refining the Error Messages in recent EOS cameras

Beginning around 2007, cameras like the EOS-1D Mark III, EOS 5D Mark II and EOS 7D started to have a more sophisticated system of error reporting to users. First, they could display their messages on the color LCD monitor, along with an explanation of the problem and a very quick listing of corrective action to try. And, rather than rely on “Error 99” as a general message for most detected problems, they added new Error Codes — in addition to codes 01~06 above — to point the photographer a bit more precisely in the direction of where the problem might be. On recent and current EOS models, these added Error Codes include:

  • Err 10: File malfunction
    Some sort of error in files written (or attempted to be written) to the memory card has been detected.
  • Err 20: Mechanical malfunction
    Within the mirror, shutter or aperture mechanism (most likely), some sort of disturbance, error or lock-up has been detected. This error code doesn’t specify where the exact problem is, but points to the cause being mechanical rather than an electronic gremlin.
  • Err 30: Shutter malfunction
    Unlike Error 20, this one does point to some sort of problem with the shutter… it could be either a mechanical problem, or some sort of electronic communication error.
  • Err 40: Power source malfunction
    An internal error in getting power from the battery to some part of the camera has been detected. Most likely, it’s not a simple weak battery, although of course a battery error is a possibility.
  • Err 50: Electronic control malfunction
    Unlike Error 20, which points to something mechanical, this one reports to the photographer that some sort of electronic error or interference with internal communication is occurring. However, it does not specify any further what or where the exact source of the malfunction may be.
  • Err 70: Image malfunction
    Something related to the data being captured and/or written to the memory card is detected as being problematic in some way… this may not be a simple memory card error, although of course that can’t be ruled out.
  • Err 80: Electronic control or image malfunction
  • Err 99: A system malfunction has been detected

Finally, there are several numbers in the sequences above that are not reported as Error Codes (such as “Err 60”); this is normal, and not an oversight.

What should you do if you encounter an error code?

First, remember that the problem might be a simple, momentary hiccup in the camera’s sequence of internal operations. If you remove the camera’s battery for a few seconds, and then re-install it, you in essence are “re-booting” the camera — much like re-starting a computer that has locked-up for whatever reason. And just as a simple re-boot is often all it takes to get your computer back up and running, it sometimes can restore order and proper operation to an EOS SLR camera. So in general, this is a step that should be performed early-on if you encounter an error message.

But that may not always work. After re-inserting the battery, the camera may continue to display the error message, or it may re-appear after you try to fire the next shot or two. Since the error codes do point to some specific areas, this can be helpful in trying to at least isolate where the problem is.

In cases where the error code points to an issue with something you attach or install in the camera — a memory card or a lens, for instance — try removing that item, and simply re-installing it, and then see if the camera allows normal operation. If not, try removing it, and installing a different card or lens (in the latter case, if at all possible, you want to try this with a Canon-brand lens — it doesn’t have to be the same focal length as the one you were using, but there can sometimes be communication error issues related to certain third-party lenses on EOS bodies, and checking this with a Canon-brand lens eliminates this as a possible factor).

Warning: do not clean lens contacts on either a Canon lens or the camera body with an eraser! It’s incredibly easy to rub off the gold plating on these contacts, and end up with data communication problems, even if that wasn’t the original source of the problem! It’s obviously a good idea to clean the contacts if a lens communication error is reported, but our strong recommendation is to use a soft, clean cloth, perhaps moistened with isopropyl alcohol if you feel the contacts are smudged with fingerprint oil or similar debris and really need a cleaning agent. Again, do not use anything abrasive, and to repeat: do not use an eraser!

With a memory card, if it’s safe to do so (think about this before you act — you don’t want to make a mistake here!), take a different card, try to format the card using the camera’s menu command, and see if that restores normal operation to the camera. If it seems to, take a couple of quick test images, and at least play them back on the camera’s LCD monitor to see if they seem OK. If so, you’re probably good to go.

The primary thing to remember is this: if you encounter an error code, try to isolate exactly WHAT it is that might be the cause of it. Maybe it is a card or lens that’s causing some sort of disturbance. Did the camera suddenly start displaying Error Codes when you connected it via USB to do some tethered shooting? Try removing the USB cable, and firing it normally to see if it now operates properly. Likewise, if you’ve attached any third-party device to it — a studio-type flash unit, a sync cord, a radio-remote trigger, and so on — bring the camera back to a state where you’ve simply got a camera, lens and card, and nothing else, and see if after re-installing a battery, normal operation seems to return. If it does, it’s a sign that somehow, the connected device(s) are creating some sort of disturbance in the camera’s operation.

If all else fails...

Sometimes, in spite of your best efforts, an error message simply keeps the camera from operating, and no amount of lens- or card-switching will bring it back to normal operation. Or, the camera may seem to return to normal for a while, but the same error message may return one or more times. If this should be the case, the camera will need to be examined by a qualified service technician. It may be prudent to send the body in with the same lens and card that were in use when the error code initially appeared, if that’s possible, since either might be a possible source of the problem.

Make a note of the specific error code reported on the camera’s LCD monitor (or the LCD panel on some older EOS models), and contact the Canon authorized factory service center in your region for specific information on where to send the camera for examination, and whether it should be sent with a photocopy of a sales receipt for proof of warranty coverage. Service personnel may not be able to diagnose the problem over the phone, but certainly have the diagnostic gear to pin-point problems once a camera has been sent to a service facility.


The nice thing about Error Codes is that they do give the user a small window into what might be the cause of a problem they’re encountering, and this give them at least a small chance to take steps to restore normal operation in the event of a minor internal problem. Rather than simply “dying” in the field with no idea of any possible cause, an Error Code does point the user in a direction to try to isolate what may have gone wrong, and in the event they cannot bring the camera back to life, it gives them something concrete to report to the service department when the camera is examined.

Perhaps most importantly, by understanding a bit about error codes, they provide at least a chance that photographers can avoid unnecessarily tying-up equipment and sending it off for service, if it turns out that a minor problem with a memory card, a lens, or a battery turned out to be the source of the error message displayed during shooting. Many EOS cameras never display any Error Codes during their lifetime. But if you do encounter one, take a few moments to think about the problem reported, and take logical steps to see if the camera can be brought back to normal operating status.

The CDLC contributors are compensated spokespersons and actual users of the Canon products that they promote.

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