Mychron 5s EGT reading going blank above 1000 degrees

Anyone seen this before? My live EGT reading on my Mychron 5s display will go to dashes instead of numbers when it gets above 1000. It’s still reading proper values in the data, the alarms still trigger when they are supposed to but the live number no longer displays? I thought it had to do with the alarms so I changed them around for a session to where I never hit them but same behavior. Little alarming on the coupld seconds you have to relax while going down the straight you look down to make sure things are healthy and can’t really tell where the EGT’s are at.


Not familiar with the M5s, but maybe it only displays 3 digits i.e. 999*. Can you set it to the display to read in 10’s of a degree? That way 1001* would read 100* or just change it to degrees C. As long as you know your targets in Fahrenheit, you can convert it to know what to look for.

I had an issue like that on my M4. I replaced the EGT sensor and it resolved it. My sensor was really old so i figured it was probably due for a change.

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Did it still record the correct temp, just not display it?

I probably should have included that replacing the sensor with a brand new one was the first thing I did with no difference. Good thought as I went down that same road.

@KartingIsLife correct, all the numbers in the data are valid just the live display of data while you’re driving quits reading at the 4 digit mark or there abouts.

Got it. My question was for Nicholas.
This might be something for AIM to look at the unit for. Very strange.

Called AIM and was informed this is a known bug on the new 5S model and they are working on a firmware update to fix it.

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Is it just a Fahrenheit issue or did you try Celsius also?

New firmware out


How to Update MyChron5 Firmware and Software
Firmware updates should be done regularly as these updates are for new options for your MyChron5 (M5) and enhance the operation of your MyChron5 product.
Please ensure all screensavers and power saving options are disabled on your PC before attempting firmware and software updates.
Please ensure that the M5 battery is fully charged before attempting any firmware and software updates.
Connect your PC to the Internet
Open Race Studio 3 (RS3)
At the top right there is a blue cloud icon
Click on the cloud - this will now show the updates available
Ensure only RS3 and MyChron5 are ticked (untick any other options)
Click on the download tab
This will now download the updates for software and firmware to your PC
Once downloaded, RS3 will ask to be installed, yes to install RS3.
Once installed and completed, disconnect your Wi-Fi connection to the internet if applicable.
Turn on your M5
Go to Wi-Fi icon in M5 menu Select auto for Wi-Fi mode Exit to main screen
Open RS3
At top right click on Wi-Fi icon
Click on your M5 serial number – this will connect your M5
Click on Firmup tab and a new window will open
Click on Update device to …version (This may take several minutes – do not turn off M5 or disconnect battery during this process)
Your M5 serial number will reappear in the update box once it has completed updating
You can then exit the update window
M5 is now updated and ready for use
AiM SportSystems Pty Ltd and its representatives are not responsible for the incorrect procedure of firmware updates that may leave the MyChron5 unusable.

New firmware again…