# 5D mark iv- Error 40



## Drum (Jun 4, 2019)

I have had my 5D4 for almost 3 years without any problems whatsoever, however it has just developed "error 40" when you turn the camera on. I have only ever used oem batteries in the camera, however they have been a mix of Lp-E6n and Lp-E6's both types of battery are compatible. I have 3 batteries two 6's and one 6n and the error comes up with all 3 batteries, if i put them into my mark 3 there is no problem, I also tried to use them via the oem battery grip and error 40 still shows up. This leads me to believe that it is a camera issue rather than a battery issue. The camera has never been exposed to water and is stored inside my house in my think tank case, it has rarely been used outside in the rain and certainly not in the last 6 months.
When I was first discovering the fault I accidentally pressed the shutter button and the fault went away, I took a couple of test shots and all seemed fine, however if the camera is turned on and off the problem reappears.
I can't get the camera to Canon service for 4 weeks as I do not trust the postal service in this country (Ireland) and major carriers like fedex or ups aren't readily available whereas I can drive to Dublin in a few weeks and deliver it in person. (Canon service doesn't do weekends and I work during the week).
So to my question, because the camera acts normally after the initial warning message, should I use it while waiting to go to service or do I risk doing more damage to whatever is causing the error?
I had posted a similar question on a facebook group and all I got back was that it was a lens connection problem. This is not a lens connection or lens related issue, as it also happens with no lenses connected to the camera.


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## BillB (Jun 4, 2019)

Drum said:


> I have had my 5D4 for almost 3 years without any problems whatsoever, however it has just developed "error 40" when you turn the camera on. I have only ever used oem batteries in the camera, however they have been a mix of Lp-E6n and Lp-E6's both types of battery are compatible. I have 3 batteries two 6's and one 6n and the error comes up with all 3 batteries, if i put them into my mark 3 there is no problem, I also tried to use them via the oem battery grip and error 40 still shows up. This leads me to believe that it is a camera issue rather than a battery issue. The camera has never been exposed to water and is stored inside my house in my think tank case, it has rarely been used outside in the rain and certainly not in the last 6 months.
> When I was first discovering the fault I accidentally pressed the shutter button and the fault went away, I took a couple of test shots and all seemed fine, however if the camera is turned on and off the problem reappears.
> I can't get the camera to Canon service for 4 weeks as I do not trust the postal service in this country (Ireland) and major carriers like fedex or ups aren't readily available whereas I can drive to Dublin in a few weeks and deliver it in person. (Canon service doesn't do weekends and I work during the week).
> So to my question, because the camera acts normally after the initial warning message, should I use it while waiting to go to service or do I risk doing more damage to whatever is causing the error?
> I had posted a similar question on a facebook group and all I got back was that it was a lens connection problem. This is not a lens connection or lens related issue, as it also happens with no lenses connected to the camera.


Have you tried it with different lenses?


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## Drum (Jun 4, 2019)

Yes, I have tried it with several different lenses, I really think it is more of a motherboard or that type of related problem rather that a lens connection related problem.


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## Random Orbits (Jun 4, 2019)

If I recall correctly, I had a similar problem on my 5D3 years ago. A board is failing inside the camera. I don't think it has much to do with the batteries.


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## miglimey (Aug 23, 2019)

I just encountered the same problem. After some research, it seems it has nothing to do with the batteries or lenses. Turns out it has to do with the Auto Sensor leaning function when you turn on the camera. If that has a problem you can get the error. You can interrupt the error by opening the CF Card door and closing it. Then disable the auto clean function in the menu. 
The camera will work fine, but you'll need to get it services to fix the sensorclean function, I believe.


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